stdlib.h File Reference

Useful generic functions and macros. More...

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Macros
#define	EXIT_SUCCESS   0
	Successful execution of a program.
#define	EXIT_FAILURE   1
	Unsuccessful execution of a program.
#define	RAND_MAX   ((1U << 31U) - 1U)
	The maximum value returned by the rand function.

Functions
size_t	malloc_usable_size (void *ptr)
	Returns the number of usable bytes in the block pointed to by ptr. More...
void *	malloc (unsigned int size)
	Provides dynamically allocated memory. More...
void *	calloc (size_t num, size_t size)
	Allocates a block of memory for an array of num elements. More...
void *	realloc (void *ptr, size_t size)
	Reallocates the given area of memory. More...
void	free (void *ptr)
	Frees dynamically allocated memory. More...
void	abort (void)
	Cause an abnormal program termination with core-dump.
int	setenv (const char *name, const char *value, int overwrite)
	Tries to adds the variable to the environment. More...
int	unsetenv (const char *name)
	Tries to remove the variable from the environment. More...
char *	getenv (const char *name)
	Returns the value of the given variable. More...
void	srand (unsigned x)
	Allows to set the seed of the random value generator. More...
unsigned	rand (void)
	Generates a random unsigned integer between 0 and RAND_MAX. More...
float	randf (void)
	Generates a random floating point number between 0 and 1. More...
int	randint (int lb, int ub)
	Generates a random integer between lb and ub. More...
unsigned	randuint (unsigned lb, unsigned ub)
	Generates a random unsigned between lb and ub. More...
float	randfloat (float lb, float ub)
	Generates a random float between lb and ub. More...

Detailed Description

Useful generic functions and macros.

Copyright

(c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Function Documentation

calloc()

void* calloc	(	size_t	num,
		size_t	size
	)

Allocates a block of memory for an array of num elements.

Parameters

num	The number of elements.
size	The size of an element.

Returns

A pointer to the allocated memory.

free()

void free

(

void *

ptr

)

Frees dynamically allocated memory.

Parameters

ptr	The pointer to the allocated memory.

getenv()

char* getenv

(

const char *

name

)

Returns the value of the given variable.

Parameters

name	Name of the variable.

Returns

A pointer to the value, or NULL if there is no match.

malloc()

void* malloc

(

unsigned int

size

)

Provides dynamically allocated memory.

Parameters

size	The amount of memory to allocate.

Returns

A pointer to the allocated memory.

malloc_usable_size()

size_t malloc_usable_size

(

void *

ptr

)

Returns the number of usable bytes in the block pointed to by ptr.

Parameters

ptr	The pointer for which we want to retrieve the usable size.

Returns

The number of usable bytes in the block of allocated memory pointed to by ptr. If ptr is not a valid pointer, 0 is returned.

rand()

unsigned rand

(

void

)

Generates a random unsigned integer between 0 and RAND_MAX.

Returns

the random value.

randf()

float randf

(

void

)

Generates a random floating point number between 0 and 1.

Returns

the random value.

randfloat()

float randfloat	(	float	lb,
		float	ub
	)

Generates a random float between lb and ub.

Parameters

lb	the lower-bound value.
ub	the upper-bound value.

Returns

the random value.

randint()

int randint	(	int	lb,
		int	ub
	)

Generates a random integer between lb and ub.

Parameters

lb	the lower-bound value.
ub	the upper-bound value.

Returns

the random value.

randuint()

unsigned randuint	(	unsigned	lb,
		unsigned	ub
	)

Generates a random unsigned between lb and ub.

Parameters

lb	the lower-bound value.
ub	the upper-bound value.

Returns

the random value.

realloc()

void* realloc	(	void *	ptr,
		size_t	size
	)

Reallocates the given area of memory.

Parameters

ptr	The pointer to the memory to reallocate.
size	The new size for the memory.

Returns

A pointer to the new portion of memory.

It must be previously allocated by malloc(), calloc() or realloc() and not yet freed with a call to free or realloc. Otherwise, the results are undefined.

setenv()

int setenv	(	const char *	name,
		const char *	value,
		int	overwrite
	)

Tries to adds the variable to the environment.

Parameters

name	Name of the variable.
value	Value of the variable.
overwrite	Override existing variable value or not.

Returns

Zero on success, or -1 on error with errno indicating the cause.

srand()

void srand

(

unsigned

x

)

Allows to set the seed of the random value generator.

Parameters

x	The new seed.

unsetenv()

int unsetenv

(

const char *

name

)

Tries to remove the variable from the environment.

Parameters

name	Name of the variable.

Returns

Zero on success, or -1 on error with errno indicating the cause.