C Reference Cheat Sheet (Page 3 of 13) in pdf

C Reference Cheat Sheet

Ashlyn Black

via

Structures (cont)

Unions

A strctName structure type pointer,

Defining

struct strctName

*ptrName;

ptrName.

A union type uName with two members, x & y.

union uName{int

Size is same as biggest member size.

Shorthand for defining strctName and

x; char y[8];}

struct strctName{ type

declaring varName as that structure

a; type b; } varName;

Declaring

type.

A variable vName as union type uN.

union uN vName;

A variable varName as structure type

struct strctName

Accessing

strctName and initialising its members.

varName = { a, b };

Members cannot store values concur r ently.

vName.y[int]

Accessing

Setting y will corrupt x.

Member x of structure varName.

varName.x

Unions are used for storing multiple data types in the same area of

Value of structure pointer ptrName

ptrName->x

memory.

member x.

Enumer a tion

Bit Fields

Defining

Declares x with two members a and b,

struct{char a:4, b:4}

both four bits in size (0 to 15.)

A custom data type bool with two possible

enum bool {

states: false or true.

false, true };

Array members can't be assigned bit fields.

Declaring

Type Defini t ions

A variable varName of data type bool.

enum bool

Defining

varName;

Abbreviating a longer type

Assigning

typedef unsigned short uint16;

name to uint16.

Variable varName can only be assigned values

varName = true;

Creating a newType from a

typedef struct structName{int

of either false or true.

structure.

a, b;}newType;

Evaluating

Creating an enumerated bool

typedef enum typeName{false,

Testing the value of varName.

if(varName ==

type.

true}bool;

false)

Declaring

Pointers

Variable x as type uint16.

uint16 x = 65535;

Structure y as type newType.

Declaring

newType y = {0, 0};

Pointers have a data type like normal variables.

type *x;

By Ashlyn Black

Published 28th January, 2015.

C Reference Cheat Sheet Page 3

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