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Better classify types according to ISO C11.

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Joshua Potter 2024-08-24 18:48:32 -06:00
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17
notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json
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"Basic": [

2
notes/_journal/2024-08/2024-08-16.md
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@ -9,4 +9,4 @@ title: "2024-08-16"
- [ ] Korean (Read 1 Story)
* Notes on [[relations#Preorders|preorders]] and [[relations#Partial Orders|partial orders]].
* Details on C's [[c17/index|abstract state machine]] and [[types|integer types]].
* Details on C's [[c17/index|abstract state machine]] and [[basic|integer types]].

372
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@ -323,378 +323,6 @@ Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Progra
<!--ID: 1722786892125-->
END%%
### Type Specifiers
Signed | Unsigned | 32-bit | 64-bit
----------- | ------------------- | ------ | ------
signed char | unsigned char | 1 | 1
short | unsigned short | 2 | 2
int | unsigned | 4 | 4
long | unsigned long | 4 | 8
long long | unsigned long long | 8 | 8
char * | - | 4 | 8
float | - | 4 | 4
double | - | 8 | 8
Fixed width data integral types (e.g. `int32_t`) can be found by including `<stdint.h>`.
%%ANKI
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.
<!--ID: 1707835869728-->
END%%
%%ANKI
Basic
Which header file contains `INT32_MAX`?
Back: `<stdint.h>`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1708615249870-->
END%%
%%ANKI
Basic
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.
<!--ID: 1707835869737-->
END%%
%%ANKI
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.
END%%
%%ANKI
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.
END%%
%%ANKI
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.
END%%
%%ANKI
Basic
How large is a word?
Back: This is a machine-dependent value.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1707657889227-->
END%%
%%ANKI
Basic
What word sizes are typical nowadays?
Back: 32- and 64-bit word sizes.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1707657889230-->
END%%
%%ANKI
Cloze
`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.
<!--ID: 1707493017164-->
END%%
%%ANKI
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.
<!--ID: 1707493017210-->
END%%
%%ANKI
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.
<!--ID: 1707493017215-->
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.
<!--ID: 1707493017219-->
END%%
%%ANKI
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.
<!--ID: 1707493017222-->
END%%
%%ANKI
Cloze
`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.
<!--ID: 1708425521263-->
END%%
%%ANKI
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.
<!--ID: 1708425521292-->
END%%
%%ANKI
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.
<!--ID: 1708425521296-->
END%%
%%ANKI
Cloze
`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.
<!--ID: 1707493017224-->
END%%
%%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.
<!--ID: 1707493017227-->
END%%
%%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.
<!--ID: 1707493017229-->
END%%
%%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.
<!--ID: 1707493017232-->
END%%
%%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.
<!--ID: 1707493017234-->
END%%
%%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.
<!--ID: 1707493017237-->
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.
<!--ID: 1707493017242-->
END%%
%%ANKI
Cloze
The C standard defines {lower} bounds on numeric ranges of data types.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1718281813453-->
END%%
%%ANKI
Cloze
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.
<!--ID: 1718281813458-->
END%%
### Structs
A `struct` is a grouping of data together. It has the following general form:
```c
struct optional_tag {
type_1 ident1;
...
type_N identN;
} optional_var1 ... optional_varM;
```
%%ANKI
Basic
What is the underlined portion of the following declaration called?
```c
struct ___ { ... };
```
Back: The tag.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892126-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
struct X { ... } X;
```
Back: The first `X` is a tag whereas the second is a variable with type `struct X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892127-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
typedef struct X { ... } X;
```
Back: The first `X` is a tag whereas the second is an alias for type `struct X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892128-->
END%%
### Unions
A `union` is a grouping of data together but with overlaid storage. It has the following general form:
```c
union optional_tag {
type1 ident1;
...
typeN identN;
} optional_var1 ... optional_varN;
```
%%ANKI
Basic
What is the underlined portion of the following declaration called?
```c
union ___ { ... };
```
Back: The tag.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892129-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
union X { ... } X;
```
Back: The first `X` is a tag whereas the second is a variable with type `union X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892130-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
typedef union X { ... } X;
```
Back: The first `X` is a tag whereas the second is an alias for type `union X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892131-->
END%%
### Enums
An `enum` is a mapping of identifiers with integer values. They have general form:
```c
enum optional_tag {
type1 ident1;
...
typeN identN;
} optional_var1 ... optional_varN;
```
%%ANKI
Basic
What is the underlined portion of the following declaration called?
```c
enum ___ { ... };
```
Back: The tag.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892132-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
enum X { ... } X;
```
Back: The first `X` is a tag whereas the second is a variable with type `enum X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892133-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
typedef enum X { ... } X;
```
Back: The first `X` is a tag whereas the second is an alias for type `enum X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892134-->
END%%
%%ANKI
Basic
What is the value of `A` in the following?
```c
enum X { A, B, C };
```
Back: `0`
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892135-->
END%%
%%ANKI
Basic
What is the value of `B` in the following?
```c
enum X { A, B, C };
```
Back: `1`
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892136-->
END%%
%%ANKI
Basic
What is the value of `B` in the following?
```c
enum X { A=2, B, C };
```
Back: `3`
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892137-->
END%%
%%ANKI
Basic
According to Linden, what is the "only advantage" of `enum`s over `#define`?
Back: `enum`s can usually be traced in a debugger.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892138-->
END%%
## Bibliography
* 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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@ -337,8 +337,6 @@ END%%
Types are additional properties that C associates with values. All values have a type that is statically determined and all possible operations on a value are determined by its type.
Types are categorized as function types and object types. An object type is **complete** if there is sufficient information to determine the size of objects of that type. Otherwise we say it is **incomplete**.
%%ANKI
Cloze
Possible operations on a {value} are determined by its {type}.
@ -346,103 +344,6 @@ Reference: Jens Gustedt, _Modern C_ (Shelter Island, NY: Manning Publications Co
<!--ID: 1723856661364-->
END%%
%%ANKI
Basic
Types are partitioned into what two categories?
Back: Object types and function types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994842-->
END%%
%%ANKI
Basic
What is an object type?
Back: A type that describes objects.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994846-->
END%%
%%ANKI
Basic
What is a function type?
Back: A type that describes functions.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994851-->
END%%
%%ANKI
Basic
What two parts characterize a function type?
Back: The return type and the number/types of its parameters.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994856-->
END%%
%%ANKI
Basic
What does it mean for an object type to be complete?
Back: There is sufficient information to determine the size of objects of that type.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994866-->
END%%
%%ANKI
Basic
What does it mean for an object type to be incomplete?
Back: There is insufficient information to determine the size of objects of that type.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994870-->
END%%
%%ANKI
Basic
Does `x` have complete or incomplete object type in the following?
```c
void x;
```
Back: Incomplete.
Reference: ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510995010-->
END%%
%%ANKI
Basic
Does `x` have complete or incomplete object type in the following?
```c
int x;
```
Back: Complete.
Reference: ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510995016-->
END%%
%%ANKI
Basic
Does `x` have complete or incomplete object type in the following?
```c
void *x;
```
Back: Complete.
Reference: ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510995023-->
END%%
%%ANKI
Basic
What object type can an lvalue *not* have?
Back: `void`
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994890-->
END%%
%%ANKI
Basic
What object type can an lvalue have?
Back: Any object type other than `void`.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994895-->
END%%
## Representation
The **binary representation** of a type is the model used to represent values of said type on a given platform. The **object representation** of a type determines how values are stored in memory, disk, etc.

23
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@ -1,23 +0,0 @@
---
title: Pointers
TARGET DECK: Obsidian::STEM
FILE TAGS: c17
tags:
- c17
---
## Overview
Pointers have the same size as the machine's word size since it should be able to refer to any virtual address.
%%ANKI
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.
<!--ID: 1707493017246-->
END%%
## Bibliography
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.

119
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@ -0,0 +1,119 @@
---
title: Derived Types
TARGET DECK: Obsidian::STEM
FILE TAGS: c17::type
tags:
- c17
---
## Overview
TODO
## Pointers
Pointers have the same size as the machine's word size since it should be able to refer to any virtual address.
%%ANKI
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.
<!--ID: 1707493017246-->
END%%
## Structures
A `struct` is a grouping of data together. It has the following general form:
```c
struct optional_tag {
type_1 ident1;
...
type_N identN;
} optional_var1 ... optional_varM;
```
%%ANKI
Basic
What is the underlined portion of the following declaration called?
```c
struct ___ { ... };
```
Back: The tag.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892126-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
struct X { ... } X;
```
Back: The first `X` is a tag whereas the second is a variable with type `struct X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892127-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
typedef struct X { ... } X;
```
Back: The first `X` is a tag whereas the second is an alias for type `struct X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892128-->
END%%
## Unions
A `union` is a grouping of data together but with overlaid storage. It has the following general form:
```c
union optional_tag {
type1 ident1;
...
typeN identN;
} optional_var1 ... optional_varN;
```
%%ANKI
Basic
What is the underlined portion of the following declaration called?
```c
union ___ { ... };
```
Back: The tag.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892129-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
union X { ... } X;
```
Back: The first `X` is a tag whereas the second is a variable with type `union X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892130-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
typedef union X { ... } X;
```
Back: The first `X` is a tag whereas the second is an alias for type `union X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892131-->
END%%
## Bibliography
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
* “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
* Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.

395
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@ -0,0 +1,395 @@
---
title: Types
TARGET DECK: Obsidian::STEM
FILE TAGS: c17::type
tags:
- c17
---
## Overview
Types in C are categorized corresponding to a hierarchy with a foundation comprising of the [[simple|simple types]]. These types are then grouped and further categorized until we reach the top of the hierarchy consisting of all types.
%%ANKI
Basic
What is the foundational category of types?
Back: The simple types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734400-->
END%%
%%ANKI
Basic
Why are "simple types" named the way they are?
Back: These types are primitives in the type hierarchy.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734408-->
END%%
%%ANKI
Basic
Why are "real types" named the way they are?
Back: They refer to types that belong to $\mathbb{R}$.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734411-->
END%%
%%ANKI
Basic
Why are "real types" named the way they are?
Back: They refer to types that belong to $\mathbb{C}$.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
END%%
All types are categorized as **function types** or **object types**. An object type is **complete** if there is sufficient information to determine the size of objects of that type. Otherwise we say it is **incomplete**.
%%ANKI
Basic
Types are partitioned into what two top-level categories?
Back: Object types and function types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994842-->
END%%
%%ANKI
Basic
What is an object type?
Back: A type that describes objects.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994846-->
END%%
%%ANKI
Basic
What is a function type?
Back: A type that describes functions.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994851-->
END%%
%%ANKI
Basic
What two parts characterize a function type?
Back: The return type and the number/types of its parameters.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994856-->
END%%
%%ANKI
Basic
What does it mean for an object type to be complete?
Back: There is sufficient information to determine the size of objects of that type.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994866-->
END%%
%%ANKI
Basic
What does it mean for an object type to be incomplete?
Back: There is insufficient information to determine the size of objects of that type.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994870-->
END%%
%%ANKI
Basic
Does `x` have complete or incomplete object type in the following?
```c
void x;
```
Back: Incomplete.
Reference: ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510995010-->
END%%
%%ANKI
Basic
Does `x` have complete or incomplete object type in the following?
```c
int x;
```
Back: Complete.
Reference: ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510995016-->
END%%
%%ANKI
Basic
Does `x` have complete or incomplete object type in the following?
```c
void *x;
```
Back: Complete.
Reference: ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510995023-->
END%%
%%ANKI
Basic
What object type can an lvalue *not* have?
Back: `void`
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994890-->
END%%
%%ANKI
Basic
What object type can an lvalue have?
Back: Any object type other than `void`.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1723510994895-->
END%%
## Basic Types
The **basic types** comprise of `char`, the signed/unsigned integer types, and the floating point types. All basic types are complete object types.
%%ANKI
Basic
Are the basic types a subset of object types or function types?
Back: Object types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734414-->
END%%
%%ANKI
Basic
The basic types consist of what simple types?
Back: `char`, signed/unsigned integer types, and the floating point types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734417-->
END%%
%%ANKI
Basic
Is `int` considered a basic type?
Back: Yes.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734421-->
END%%
%%ANKI
Basic
Is `char` considered a simple type?
Back: Yes.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734424-->
END%%
%%ANKI
Basic
Is `float complex` considered a simple type?
Back: Yes.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734428-->
END%%
## Integer Types
The **integer types** comprise of `char`, the signed/unsigned integer types, and `enum`s.
%%ANKI
Basic
Are the integer types a subset of object types or function types?
Back: Object types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734431-->
END%%
%%ANKI
Basic
The integer types consist of what simple types?
Back: `char`, signed/unsigned integer types, and `enum`s.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734436-->
END%%
%%ANKI
Basic
Is `enum` considered a simple type?
Back: Yes.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734439-->
END%%
%%ANKI
Basic
Is `enum` considered a basic type?
Back: No.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734443-->
END%%
%%ANKI
Basic
Is `enum` considered a complex type?
Back: No.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734447-->
END%%
%%ANKI
Basic
Is `enum` considered a real type?
Back: Yes.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734452-->
END%%
%%ANKI
Basic
What category of types is considered a basic type but not an integer type?
Back: Floating point types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734458-->
END%%
%%ANKI
Basic
What category of types is considered an integer type but not a basic type?
Back: Enumerated types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734463-->
END%%
%%ANKI
Basic
Which types are considered both basic types and integer types?
Back: `char` and the signed/unsigned integer types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734469-->
END%%
%%ANKI
Basic
Which of basic types or integer types is a subset of the other?
Back: N/A.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734477-->
END%%
## Arithmetic Types
Integer and floating point types are collectively called **arithmetic types**. Each arithmetic type belongs to one **type domain**: the **real type domain** comprises the real types and the **complex type domain** comprises the complex types.
%%ANKI
Cloze
Integer and floating point types are collectively called {arithmetic} types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977383-->
END%%
%%ANKI
Cloze
The {real} types contrast the {complex} types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977387-->
END%%
%%ANKI
Basic
Which two smaller category of types make up the arithmetic types?
Back: The integer and floating point types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977391-->
END%%
%%ANKI
Basic
The arithmetic types are categorized into what type domains?
Back: The real type domain and the complex type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977395-->
END%%
%%ANKI
Basic
Which type domain does `int` fall under?
Back: The real type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977399-->
END%%
%%ANKI
Basic
Which type domain does `float complex` fall under?
Back: The complex type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977404-->
END%%
%%ANKI
Basic
Which type domain does `float` fall under?
Back: The real type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977408-->
END%%
%%ANKI
Basic
Which type domain does `long double` fall under?
Back: The real type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977412-->
END%%
%%ANKI
Basic
Which type domain does `bool` fall under?
Back: The real type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977417-->
END%%
%%ANKI
Basic
Which type domain does `double complex` fall under?
Back: The complex type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724543977422-->
END%%
%%ANKI
Basic
Which of basic types or arithmetic types is a subset of the other?
Back: Basic types is a subset of arithmetic types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734484-->
END%%
%%ANKI
Basic
Which of arithmetic types or integer types is a subset of the other?
Back: Integer types is a subset of arithmetic types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734489-->
END%%
%%ANKI
Basic
Which of the real types or integer types is a subset of the other?
Back: The integer types is a subset of the real types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734493-->
END%%
%%ANKI
Basic
Which of the real types or floating point types is a subset of the other?
Back: N/A.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734498-->
END%%
%%ANKI
Basic
Which types belong to the intersection of real and floating point types?
Back: Floating point types in the real type domain.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546734502-->
END%%
## Bibliography
* “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).

315
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@ -1,16 +1,231 @@
---
title: Types
title: Simple Types
TARGET DECK: Obsidian::STEM
FILE TAGS: c17
FILE TAGS: c17::type
tags:
- c17
---
## Overview
C has a series of basic types and means of constructing derived types from them.
The bottom of the type hierarchy consists of **simple types**. This comprises the primitive types that all other types are either based off of or derived from.
## Integers
| Signed | Unsigned | 32-bit | 64-bit |
| ------------- | -------------------- | ------ | ------ |
| - | `bool` | 1 | 1 |
| `signed char` | `unsigned char` | 1 | 1 |
| `short` | `unsigned short` | 2 | 2 |
| `int` | `unsigned` | 4 | 4 |
| `long` | `unsigned long` | 4 | 8 |
| `long long` | `unsigned long long` | 8 | 8 |
| Real | Complex | 32-bit | 64-bit |
| ------------- | --------------------- | ------ | ------ |
| `float` | - | 4 | 4 |
| `double` | - | 8 | 8 |
| `long double` | - | - | - |
| - | `float complex` | 4 | 4 |
| - | `double complex` | 8 | 8 |
| - | `long double complex` | - | - |
%%ANKI
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.
<!--ID: 1707835869728-->
END%%
%%ANKI
Basic
The integer types are grouped into what two classes?
Back: The signed and unsigned integer types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546870212-->
END%%
%%ANKI
Basic
The floating point types are grouped into what two classes?
Back: The real and complex floating point types.
Reference: “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
<!--ID: 1724546870217-->
END%%
%%ANKI
Basic
Which header file contains `INT32_MAX`?
Back: `<stdint.h>`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1708615249870-->
END%%
%%ANKI
Basic
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.
<!--ID: 1707835869737-->
END%%
%%ANKI
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.
END%%
%%ANKI
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.
END%%
%%ANKI
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.
END%%
%%ANKI
Basic
How large is a word?
Back: This is a machine-dependent value.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1707657889227-->
END%%
%%ANKI
Basic
What word sizes are typical nowadays?
Back: 32- and 64-bit word sizes.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1707657889230-->
END%%
%%ANKI
Cloze
`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.
<!--ID: 1707493017164-->
END%%
%%ANKI
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.
<!--ID: 1707493017210-->
END%%
%%ANKI
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.
<!--ID: 1707493017215-->
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.
<!--ID: 1707493017219-->
END%%
%%ANKI
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.
<!--ID: 1707493017222-->
END%%
%%ANKI
Cloze
`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.
<!--ID: 1708425521263-->
END%%
%%ANKI
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.
<!--ID: 1708425521292-->
END%%
%%ANKI
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.
<!--ID: 1708425521296-->
END%%
%%ANKI
Cloze
`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.
<!--ID: 1707493017224-->
END%%
%%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.
<!--ID: 1707493017227-->
END%%
%%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.
<!--ID: 1707493017229-->
END%%
%%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.
<!--ID: 1707493017232-->
END%%
%%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.
<!--ID: 1707493017234-->
END%%
%%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.
<!--ID: 1707493017237-->
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.
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END%%
%%ANKI
Cloze
The C standard defines {lower} bounds on numeric ranges of data types.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1718281813453-->
END%%
%%ANKI
Cloze
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.
<!--ID: 1718281813458-->
END%%
## Characters
Type `char` is special since it can be signed or unsigned depending on platform. Keep in mind regardless of its signedness, it is still considered a distinct type from both the `unsigned char` and `signed char` type.
@ -22,6 +237,8 @@ Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Program
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END%%
## Integers
**Narrow types** cannot be used directly in arithmetic. Instead they are first promoted to a wider type. On almost every system, this promotion will be to a `signed int` of the same value, regardless of the signedness of the narrow type itself.
%%ANKI
@ -638,7 +855,93 @@ Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Program
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END%%
## Enumerated Types
An `enum` is a mapping of identifiers with integer values. They have general form:
```c
enum optional_tag {
type1 ident1;
...
typeN identN;
} optional_var1 ... optional_varN;
```
%%ANKI
Basic
What is the underlined portion of the following declaration called?
```c
enum ___ { ... };
```
Back: The tag.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892132-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
enum X { ... } X;
```
Back: The first `X` is a tag whereas the second is a variable with type `enum X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892133-->
END%%
%%ANKI
Basic
What distinguishes the `X`'s from one another in the following?
```c
typedef enum X { ... } X;
```
Back: The first `X` is a tag whereas the second is an alias for type `enum X`.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892134-->
END%%
%%ANKI
Basic
What is the value of `A` in the following?
```c
enum X { A, B, C };
```
Back: `0`
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892135-->
END%%
%%ANKI
Basic
What is the value of `B` in the following?
```c
enum X { A, B, C };
```
Back: `1`
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892136-->
END%%
%%ANKI
Basic
What is the value of `B` in the following?
```c
enum X { A=2, B, C };
```
Back: `3`
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892137-->
END%%
%%ANKI
Basic
According to Linden, what is the "only advantage" of `enum`s over `#define`?
Back: `enum`s can usually be traced in a debugger.
Reference: Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.
<!--ID: 1722786892138-->
END%%
## Bibliography
* 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).
* “ISO: Programming Languages - C,” April 12, 2011, [https://port70.net/~nsz/c/c11/n1570.pdf](https://port70.net/~nsz/c/c11/n1570.pdf).
* Van der Linden, Peter. _Expert C Programming: Deep C Secrets_. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.