1068 lines
42 KiB
Markdown
1068 lines
42 KiB
Markdown
---
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title: Strings
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TARGET DECK: Obsidian::STEM
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FILE TAGS: c17
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tags:
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- c17
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---
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## Overview
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A contiguous sequence of characters terminated by the `NUL` character (refer to [[ascii|ASCII]]). Text data is said to be more platform-independent than [[endianness|binary]] data since it is unaffected by word size or byte ordering.
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%%ANKI
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Basic
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What is a C-style string?
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Back: A character array terminated with a `NUL` character.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1707758281264-->
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END%%
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%%ANKI
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Basic
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What character terminates all C-style strings?
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Back: `NUL`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1707758281266-->
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END%%
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%%ANKI
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Basic
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What is the decimal value of `NUL` in ASCII encoding?
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Back: `0`
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1707758281268-->
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END%%
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%%ANKI
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Basic
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Text is more platform-independent than binary because it is unaffected by what two properties?
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Back: Word size and byte ordering.
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Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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<!--ID: 1707758281270-->
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END%%
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## `printf`
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The syntax for the format placeholder is `%[flags][width][.precision][length]specifier`.
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%%ANKI
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Basic
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What four optional parts make up a `printf` argument?
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Back: Flags, width, precision, and length.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708974221761-->
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END%%
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%%ANKI
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Basic
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Which header file contains basic `printf` functionality?
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Back: `<stdio.h>`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441467-->
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END%%
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%%ANKI
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Cloze
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{1:`width`} specifies a {2:minimum} while {2:`precision`} specifies a {1:maximum}.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441472-->
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END%%
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%%ANKI
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Cloze
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The {`width` and `precision`} fields are output related whereas the {`length`} field is input related.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708425941269-->
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END%%
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| Flag | Description |
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| ---- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `-` | Left-aligns the output |
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| `+` | Prepends a plus for positive signed-numeric types |
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| `␣` | Prepends a space for positive signed-numeric types |
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| `0` | Prepends zeros for numeric types |
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| `#` | For `g` and `G`, trailing zeros are not removed. For `f`, `F`, `e`, `E`, `g`, and `G`, output always has a decimal point. For `o`, `x`, and `X`, the text `0`, `0x`, and `0X` is prepended to nonzero numbers respectively. |
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%%ANKI
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Cloze
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The {`-`} flag {left-aligns the output}.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756812-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%-2d abc", 100)`?
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Back: `100␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441477-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%-4d abc", 100)`?
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Back: `100␣␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441481-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%.4d abc", 100)`?
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Back: `0100␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441486-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%04d abc", 100)`?
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Back: `0100␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441491-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%.4s abc", "efg")`?
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Back: `efg␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441495-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%.2s abc", "efg")`?
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Back: `ef␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441499-->
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END%%
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%%ANKI
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Basic
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What is the output of `printf("%.2f abc", 0.01234)`?
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Back: `0.01␣abc`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441503-->
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END%%
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%%ANKI
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Basic
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How does the precision field affect `"%s"` parameters?
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Back: Strings are truncated if longer than the specified precision.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441507-->
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END%%
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%%ANKI
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Basic
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How does the precision field affect `"%f"` parameters?
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Back: Decimal values are truncated if longer than the specified precision.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441511-->
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END%%
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%%ANKI
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Basic
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What does a negative width field value indicate?
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Back: This is actually a positive width with a `-` (left-align) flag.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708384441515-->
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END%%
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%%ANKI
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Basic
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The `-` `printf` flag overrides what default behavior?
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Back: Output is right-aligned by default.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756840-->
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END%%
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%%ANKI
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Cloze
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The {`+`} `printf` flag {prepends a plus for positive signed-numeric types}.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756846-->
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END%%
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%%ANKI
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Basic
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The `+` `printf` flag overrides what default behavior?
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Back: Nothing is prepended to positive signed-numeric types by default.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756852-->
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END%%
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%%ANKI
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Cloze
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The {`␣`} `printf` flag {prepends a space for positive signed-numeric types}.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756856-->
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END%%
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%%ANKI
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Basic
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The `␣` `printf` flag overrides what default behavior?
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Back: Nothing is prepended to positive signed-numeric types by default.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756861-->
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END%%
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%%ANKI
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Basic
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How do the `+` and `␣` `printf` flags relate to one another?
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Back: Both prepend a character to positive signed-numeric types.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756865-->
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END%%
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%%ANKI
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Basic
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What happens if both the `+` and `␣` `printf` flags are specified?
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Back: The `+` flag takes precedence.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756870-->
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END%%
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%%ANKI
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Cloze
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The {`0`} `printf` flag {prepends zeros for numeric types}.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756875-->
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END%%
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%%ANKI
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Basic
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What option must be specified for the `0` `printf` flag to take effect?
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Back: The "width" option.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756881-->
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END%%
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%%ANKI
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Basic
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The `0` `printf` flag overrides what default behavior?
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Back: Spaces are used to match the "width" option by default.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1707918756888-->
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END%%
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%%ANKI
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Basic
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How is `%#g` different from `%g`?
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Back: The former always includes a decimal point and may include trailing `0`s.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807973-->
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END%%
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%%ANKI
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Basic
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How is `%#f` different from `%f`?
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Back: The former always includes a decimal point.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807976-->
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END%%
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%%ANKI
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Basic
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How is `%#e` different from `%e`?
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Back: The former always includes a decimal point.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807979-->
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END%%
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%%ANKI
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Basic
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Which `printf` flag can be used to ensure decimal points in the output of floating-point types?
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Back: `#`
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807981-->
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END%%
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%%ANKI
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Basic
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How is `%#o` different from `%o`?
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Back: The former prepends a `0` to the output.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807983-->
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END%%
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%%ANKI
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Basic
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How is `%#x` different from `%x`?
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Back: The former prepends a `0x` to the output.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807986-->
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END%%
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%%ANKI
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Basic
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How is `%#X` different from `%X`?
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Back: The former prepends a `0X` to the output.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807988-->
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END%%
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%%ANKI
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Cloze
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`%#o` is to {`0`} as `%#x` is to {`0x`}.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1710673807990-->
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END%%
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Length | Description
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--------- | -----------
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`hh` | `int` sized integer argument promoted from a `char`
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`h` | `int` sized integer argument promoted from a `short`
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`l` | `long` sized integer argument
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`ll` | `long long` sized integer argument
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`z` | `size_t` sized integer argument
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%%ANKI
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Basic
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*Why* do length modifiers for e.g. `char` exist?
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Back: For maximum portability in the face of default argument promotions.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708426673637-->
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END%%
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%%ANKI
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Cloze
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The {`hh`} length corresponds to the {`char`} type declaration.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708426673664-->
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END%%
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%%ANKI
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Cloze
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The {`h`} length corresponds to the {`short`} type declaration.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708426673668-->
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END%%
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%%ANKI
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Cloze
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The {`l`} length corresponds to the {`long`} type declaration.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708426673711-->
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END%%
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%%ANKI
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Cloze
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The {`ll`} length corresponds to the {`long long`} type declaration.
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Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
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<!--ID: 1708426673719-->
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END%%
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%%ANKI
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|
Cloze
|
|
The {`z`} length corresponds to the {`size_t`} type declaration.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
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Tags: printf
|
|
<!--ID: 1708426673725-->
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|
END%%
|
|
|
|
Specifier | Description
|
|
--------- | -----------
|
|
`d`, `i` | a decimal `signed int`
|
|
`u` | a decimal `unsigned int`
|
|
`x`, `X` | a hexadecimal `unsigned int`
|
|
`o` | an octal `unsigned int`
|
|
`f`, `F` | a `double` in fixed-point notation
|
|
`e`, `E` | a `double` in standard notation
|
|
`g`, `G` | a `double` in normal or standard notation
|
|
`s` | a `NUL`-terminated string
|
|
`c` | a `char` character
|
|
`p` | `void*` address in an implementation-defined format
|
|
|
|
%%ANKI
|
|
Basic
|
|
What character do `printf` format specifiers start with?
|
|
Back: `%`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083029-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Why is `printf` named the way it is?
|
|
Back: It stands for **print f**ormatted.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083037-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%d` and `%i`} format specifers work on a {decimal `signed int`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083040-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
{`%d` and `%i`} are to `signed` as {`%u`} is to `unsigned`.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083044-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%u`} format specifier outputs a {decimal `unsigned int`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083047-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What distinguishes format specifiers `%d` and `%i`?
|
|
Back: Nothing.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083050-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifiers were probably used to yield `printf` output `-12`?
|
|
Back: `%d` or `%i`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083054-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What distinguishes format specifiers `%d` and `%u`?
|
|
Back: The former is for signed integers, the latter unsigned.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083058-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%x`} format specifier outputs a {lowercase hexadecimal `unsigned int`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083063-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier were probably used to yield `printf` output `7af`?
|
|
Back: `%x`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083068-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%X`} format specifier outputs an {uppercase hexadecimal `unsigned int`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083074-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier were probably used to yield `printf` output `7AF`?
|
|
Back: `%X`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083080-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What distinguishes format specifiers `%x` and `%X`?
|
|
Back: The former outputs lowercase hex digits, the latter uppercase.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083086-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%f`} format specifier outputs a {lowercase fixed-point `double`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347005-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%F`} format specifier outputs an {uppercase fixed-point `double`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347008-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What distinguishes format specifiers `%f` and `%F`?
|
|
Back: The former outputs lowercase identifiers, the latter uppercase.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347010-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What three special identifiers might specifier `%f` output?
|
|
Back: `inf`, `infinity`, and `nan`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347012-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Assuming round-to-even, what is the output of `printf("%.0f", 3.5)`?
|
|
Back: `4`
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1710675908301-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Assuming round-to-even, what is the output of `printf("%.0f", 2.5)`?
|
|
Back: `2`
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1710675908304-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
How does the C standard define the rounding mode of floating-point specifiers?
|
|
Back: This is implementation specific.
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1710675908306-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What does the rounding mode of floating-point specifiers refer to?
|
|
Back: How numbers with greater than the specified precision are output.
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1710675908307-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What three special identifiers might specifier `%F` output?
|
|
Back: `INF`, `INFINITY`, and `NAN`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450452444-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier was probably used to yield `printf` output `inf`?
|
|
Back: `%f`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347014-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
{1:Fixed-point} notation is to {2:`%f`} whereas {2:standard/exponential} notation is to {1:`%e`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347015-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier was probably used to yield `printf` output `172.345000`?
|
|
Back: `%f`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347017-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What term describes the kind of output notation corresponding to `%f`?
|
|
Back: Fixed-point notation.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347018-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What distinguishes format specifiers `%e` and `%E`?
|
|
Back: The former outputs an `e`, the latter an `E`.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347020-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
How many digits follows `e` in the output of `printf` specifier `%e`?
|
|
Back: At least `2`.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450452447-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifiers correspond to scientific notation?
|
|
Back: `%e` and `%E`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710556915108-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier was probably used to yield `printf` output `1.723450e+02`?
|
|
Back: `%e`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347022-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What is the default precision of `%f`?
|
|
Back: `6`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710452502031-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What is the output of `printf("%e", 3.14)`?
|
|
Back: `3.140000e00`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347023-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What is the output of `printf("%e", 314)`?
|
|
Back: `3.140000e02`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347025-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What term describes the kind of output notation corresponding to `%e`?
|
|
Back: Standard or exponential notation.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710450347026-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What is the default precision of `%e`?
|
|
Back: `6`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710452502034-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%g`} format specifier outputs a {lowercase `double` in fixed-point or standard notation}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710599835115-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%G`} format specifier outputs a {uppercase `double` in fixed-point or standard notation}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710844199536-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
The `%g` format specifier subsumes functionality of what other format specifiers?
|
|
Back: `%f` and `%e`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710599806326-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
The `%G` format specifier subsumes functionality of what other format specifiers?
|
|
Back: `%F` and `%E`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710599806328-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
How does `%g` handle integral values differently from `%f`?
|
|
Back: It excludes a trailing `.` and insignificant `0`s.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710603411171-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
How does `%g` handle non-integral values differently from `%f`?
|
|
Back: It excludes insignifant `0`s after the decimal point.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710603411174-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What distinguishes `%g` from `%G`?
|
|
Back: The former uses lowercase letters. The latter uses uppercase letters.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710599806331-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Assuming fixed-point notation, what is the output of `printf("%g", 3.14)`?
|
|
Back: `3.14`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
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Tags: printf
|
|
<!--ID: 1710599806333-->
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|
END%%
|
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|
%%ANKI
|
|
Basic
|
|
Assuming fixed-point notation, what is the output of `printf("%g", 3)`?
|
|
Back: `3`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710599806334-->
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|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What is the output of `printf("%f", 3)`?
|
|
Back: `3.000000`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1710599806336-->
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|
END%%
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|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%o`} format specifier outputs an {octal `unsigned int`}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083091-->
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|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Why doesn't the `%o` format specifier have a corresponding `%O` specifier?
|
|
Back: There is no distinction between lower and uppercase octal digits.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083096-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%s`} format specifiers outputs a {`NUL`-terminated string}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083100-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier was probably used to yield `printf` output `abc`?
|
|
Back: `%s`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083105-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%c`} format specifier outputs a {`char` character}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083109-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier was probably used to yield `printf` output `a`?
|
|
Back: `%c`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083113-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
The {`%p`} format specifier outputs a {`void*` address}.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083117-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which format specifier was probably used to yield `printf` output `0b80000000`?
|
|
Back: `%p`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083121-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
How is the address outputted by the `%p` format specifier written?
|
|
Back: In an implementation-specific way.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1707852083126-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Given `int64_t x`, why is `printf("%d", x)` a problem?
|
|
Back: `%d` matches an `int` which is not necessarily 64-bits.
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1708454462772-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What must you use when invoking `printf` with a fixed-width integer type?
|
|
Back: `printf`-specific macros.
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1708454462777-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What is `PRId32` an example macro for?
|
|
Back: A macro that expands to the correct specifier for a 32-bit signed integral type.
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1708454462780-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Cloze
|
|
{`PRId32`} is to signed whereas {`PRIu32`} is to unsigned.
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1708454462784-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Which C header specifies `printf` macros for fixed-width integral types?
|
|
Back: `<inttypes.h>`
|
|
Reference: “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|
|
Tags: printf
|
|
<!--ID: 1708454462788-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Given `int32_t x`, how might we invoke `printf` on it?
|
|
Back: `printf("%" PRId32, x)`
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1708454584564-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What prefix do `printf` macros from `<inttypes.h>` share?
|
|
Back: `PRI`
|
|
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
Tags: printf
|
|
<!--ID: 1708454584568-->
|
|
END%%
|
|
|
|
## Escape Sequences
|
|
|
|
C has a standard for processing different escape sequences. Many languages built with C in mind parse these escape sequences in a similar way.
|
|
|
|
* `\ooo`: Consists of one to three octal digits.
|
|
* [[bash/index|Bash]] supports this sequence as `$'\ooo'`.
|
|
|
|
%%ANKI
|
|
Basic
|
|
How are C escape sequences for octal digits denoted?
|
|
Back: As `\ooo`.
|
|
Reference: Brian W. Kernighan and Dennis M. Ritchie, *The C Programming Language*, 2nd ed (Englewood Cliffs, N.J: Prentice Hall, 1988).
|
|
<!--ID: 1706975891805-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
In C, `\ooo` allows specifying how many octal digits?
|
|
Back: One to three.
|
|
Reference: Brian W. Kernighan and Dennis M. Ritchie, *The C Programming Language*, 2nd ed (Englewood Cliffs, N.J: Prentice Hall, 1988).
|
|
<!--ID: 1706975891810-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
How are C escape sequences exposed in bash?
|
|
Back: Using ANSI-C quoting, i.e. `$$'string'`.
|
|
Reference: Mendel Cooper, “Advanced Bash-Scripting Guide,” n.d., 916.
|
|
Tags: bash
|
|
<!--ID: 1706975891817-->
|
|
END%%
|
|
|
|
* `\xhh`: Consists of one or more [[radices#Hexadecimal|hexadecimal]] digits. The `x` prefix is required to distinguish from octal escape sequences.
|
|
* [[bash/index|Bash]] supports this sequence as `$'\xhh'`. One or two digits is supported.
|
|
|
|
%%ANKI
|
|
Basic
|
|
How are C escape sequences for hexadecimal digits denoted?
|
|
Back: As `\xhh`.
|
|
Reference: Brian W. Kernighan and Dennis M. Ritchie, *The C Programming Language*, 2nd ed (Englewood Cliffs, N.J: Prentice Hall, 1988).
|
|
<!--ID: 1706975891820-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
In C, `\x` allows specifying how many hexadecimal digits?
|
|
Back: One or more.
|
|
Reference: Brian W. Kernighan and Dennis M. Ritchie, *The C Programming Language*, 2nd ed (Englewood Cliffs, N.J: Prentice Hall, 1988).
|
|
<!--ID: 1706975891824-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
What footgun does C's `\x` sequence expose?
|
|
Back: Using more than two hexadecimal digits can produce undefined results.
|
|
Reference: Arnold D. Robbins, “GAWK: Effective AWK Programming,” October 2023, [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf).
|
|
<!--ID: 1706975891828-->
|
|
END%%
|
|
|
|
* `\uhhhh`: Introduced in C11 to represent Unicode code points. *Must* have exactly four hexadecimal characters specified with `0` leading padding if necessary.
|
|
* [[bash/index|Bash]] supports this sequence as `$'uhhhh'`. One to four hex digits is supported.
|
|
|
|
%%ANKI
|
|
Basic
|
|
What two ways are C escape sequences for unicode denoted?
|
|
Back: As `\uhhhh` or `\Uhhhhhhhh`.
|
|
Reference: Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co, 2020).
|
|
Tags: encoding::unicode
|
|
<!--ID: 1706975891832-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
In C, `\u` allows specifying how many hexadecimal digits?
|
|
Back: Exactly four.
|
|
Reference: Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co, 2020).
|
|
Tags: encoding::unicode
|
|
<!--ID: 1706975891835-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
In what standard were C's `\u` and `\U` escape sequences introduced?
|
|
Back: C11.
|
|
Reference: Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co, 2020).
|
|
Tags: encoding::unicode
|
|
<!--ID: 1706975891839-->
|
|
END%%
|
|
|
|
* `\Uhhhhhhhh`: Introduced in C11 to represent larger unicode code points. *Must* have exactly eight hexadecimal characters specified with `0` leading padding if necessary.
|
|
|
|
%%ANKI
|
|
Basic
|
|
In C, `\U` allows specifying how many hexadecimal digits?
|
|
Back: Exactly eight.
|
|
Reference: Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co, 2020).
|
|
Tags: encoding::unicode
|
|
<!--ID: 1706975891843-->
|
|
END%%
|
|
|
|
%%ANKI
|
|
Basic
|
|
Why does C have both `\u` and `\U`?
|
|
Back: `\U` accommodates for larger code point values.
|
|
Reference: Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co, 2020).
|
|
Tags: encoding::unicode
|
|
<!--ID: 1706976705750-->
|
|
END%%
|
|
|
|
## References
|
|
|
|
* Arnold D. Robbins, “GAWK: Effective AWK Programming,” October 2023, [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf).
|
|
* Brian W. Kernighan and Dennis M. Ritchie, *The C Programming Language*, 2nd ed (Englewood Cliffs, N.J: Prentice Hall, 1988).
|
|
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
|
|
* Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co, 2020).
|
|
* Mendel Cooper, “Advanced Bash-Scripting Guide,” n.d., 916.
|
|
* “Printf,” in *Wikipedia*, January 18, 2024, [https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962](https://en.wikipedia.org/w/index.php?title=Printf&oldid=1196716962).
|