C declarations were designed so that the declaration of an object looks like the use of the object. This isn't quite true - keywords like `volatile` and `const` only exist in declarations - but for the most part, this philosophy can be leveraged to read C declarations.
## Declarators
A **declarator** in C is roughly an identifier along with pointers, function brackets, or array indications. Pointers will look like one of:
*`*`
*`* const`
*`* volatile`
*`* const volatile`
*`* volatile const`
whereas **direct declarators** will look like one of:
*`identifier`
*`identifier[size]`
*`identifier(args)`
*`(declarator)`
## Declarations
A **declaration** is then at least one type-specifier (e.g. `signed short`), storage class (e.g. `static`), and/or type qualifier (e.g. `const`) followed by one or more declarators.
Fixed width data integral types (e.g. `int32_t`) can be found by including `<stdint.h>`.
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Cloze
The {`<stdint.h>`} header file contains {fixed width data integral types}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
What does the "width" of an integer type refer to?
Back: The number of bits used to represent its value.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
What two variants does a C integral type declaration have?
Back: Signed and unsigned.
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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What does it mean for an integer to be "signed"?
Back: It can represent negative, zero, and positive values.
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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What does it mean for an integer to be "unsigned"?
Back: It can only represent nonnegative values.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
`char`*typically* represents {1} byte(s) on a 64-bit platform.
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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Cloze
`short`*typically* represents {2} byte(s) on a 64-bit platform.
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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Cloze
`int`*typically* represents {4} bytes(s) on a 64-bit platform.
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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END%%
%%ANKI
Cloze
`unsigned`*typically* represents {4} bytes(s) on a 64-bit platform.
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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Cloze
`long`*typically* represents {8} bytes(s) on a 64-bit platform.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
`long long`*typically* represents {8} bytes(s) on a 64-bit platform.
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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Basic
What distinguishes `long` from `long long`?
Back: `long long`s are guaranteed to be at least 64-bit wide.
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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Basic
*Why* is there both a `long` and `long long`?
Back: `long long`s are at least 64-bit wide, even on 32-bit platforms.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
`char *`*typically* represents {8} bytes(s) on a 64-bit platform.
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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%%ANKI
Cloze
`float`*typically* represents {4} bytes(s) on a 64-bit platform.
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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%%ANKI
Cloze
`double`*typically* represents {8} bytes(s) on a 64-bit platform.
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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%%ANKI
Basic
Is declaration `int` signed or unsigned?
Back: Signed.
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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%%ANKI
Basic
How is declaration `unsigned` written more precisely?
Back: `unsigned int`.
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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%%ANKI
Basic
Is declaration `long` signed or unsigned?
Back: Signed.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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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END%%
%%ANKI
Cloze
{1:`float`} has {2:4} byte precision whereas {2:`double`} has {1:8} byte precision.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
The C standard does *not* define {1:upper} bounds on numeric ranges of data types (except for {1:fixed-size} types).
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Negative integer literals are typed in a counterintuitive way. When the compiler sees a number of form `-X`, the type of `X` is determined *before* being negated. Promotion rules are as follows:
How does the compiler process integer literal `-X`?
Back: By first determining the type of `X` and then negating the value.
Reference: Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Back: Depending on value, the resulting type may be `unsigned`.
Reference: Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: 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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Cloze
Octal literals are to {`0`} whereas hexadecimal literals are to {`0x`/`0X`}.
Reference: Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: 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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%%ANKI
Basic
Which header file contains `INT_MAX`?
Back: `<limits.h>`
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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END%%
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Cloze
{`INT_MAX`} is to `signed` whereas {`UINT_MAX`} is to `unsigned`.
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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Basic
How does `<limits.h>` define `INT_MIN`?
Back: As `(-INT_MAX - 1)`.
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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END%%
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Basic
*Why* is `INT_MIN` defined as `(-INT_MAX - 1)` instead of directly as e.g. `-2147483648`?
Back: Because `2147483648` (without `-`) would be sized as a non-`int` before being negated.
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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END%%
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Cloze
`INT_MAX` is to {`<limits.h>`} whereas `INT32_MAX` is to {`<stdint.h>`}.
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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END%%
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Basic
What suffix can be used to denote an `unsigned` integer literal?
Back: Case-insensitive `U`.
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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END%%
%%ANKI
Basic
What suffix can be used to denote a `long` integer literal?
Back: Case-insensitive `L`.
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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END%%
%%ANKI
Basic
What suffix can be used to denote a `long long` integer literal?
Back: Case-insensitive `LL`.
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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END%%
%%ANKI
Basic
What suffix can be used to denote an `unsigned long long` integer literal?
Back: Case-insensitive `ULL`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
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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END%%
%%ANKI
Basic
In what order does C cast "signedness" and size?
Back: C casts size then signedness.
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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END%%
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Basic
Given `short sx`, cast `(unsigned) sx` is more explicitly written as what other sequence of casts?
Back: `(unsigned) (int) sx`
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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%%ANKI
Basic
Given `short sx`, are the following two lines equivalent?
```c
(unsigned) sx
(unsigned) (int) sx
```
Back: Yes.
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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END%%
%%ANKI
Basic
Given `short sx`, are the following two lines equivalent?
```c
(unsigned) sx
(unsigned) (unsigned short) sx
```
Back: No.
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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END%%
%%ANKI
Basic
Given `short sx`, why is the following not an identity?
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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END%%
%%ANKI
Basic
What does "signedness" of a variable refer to?
Back: Whether the variable was declared `signed` or `unsigned`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Pointers have the same size as the machine's word size since it should be able to refer to any virtual address.
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Basic
*Why* does a pointer's size match the machine's word size?
Back: Because it should be able to refer to any virtual address.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
* Peter Van der Linden and Peter VanDerLinden, _Expert C Programming: Deep C Secrets_, Programming Languages / C (Mountain View, Cal.: SunSoft Pr, 1994).
