C Library - <stdlib.h>

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Introduction

The stdlib .h header defines four variable types, several macros and various functions for performing general functions.

Library Variables

Following are the variable types defined in the header stdlib.h:

S.N.Variable & Description
1size_t
This is the unsigned integral type and is the result of the sizeof keyword.
2wchar_t
This is an integer type of the size of a wide character constant.
3div_t
This is the structure returned by the div function.
4ldiv_t
This is the structure returned by the ldiv function.

Library Macros

Following are the macros defined in the header stdlib.h:

S.N.Macro & Description
1NULL
This macro is the value of a null pointer constant.
2EXIT_FAILURE
This is the value for the exit function to return in case of failure.
3EXIT_SUCCESS
This is the value for the exit function to return in case of success.
4RAND_MAX
This macro is the maximum value returned by the rand function.
5MB_CUR_MAX
This macro is the maximum number of bytes in a multibyte character set which cannot be larger than MB_LEN_MAX.

Library Functions

Following are the functions defined in the header stdio.h:

S.N.Function & Description
1double atof(const char *str)
Converts the string pointed to by the argument str to a floating-point number (type double).
2int atoi(const char *str)
Converts the string pointed to by the argument str to an integer (type int).
3long int atol(const char *str)
Converts the string pointed to by the argument str to a long integer (type long int)
4double strtod(const char *str, char **endptr)
Converts the string pointed to by the argument str to a floating-point number (type double).
5long int strtol(const char *str, char **endptr, int base)
Converts the string pointed to by the argument str to a long integer (type long int).
6unsigned long int strtoul(const char *str, char **endptr, int base)
Converts the string pointed to by the argument str to an unsigned long integer (type unsigned long int).
7void *calloc(size_t nitems, size_t size)
Allocates the requested memory and returns a pointer to it.
8void free(void *ptr
Deallocates the memory previously allocated by a call to calloc, malloc, or realloc.
9void *malloc(size_t size)
Allocates the requested memory and returns a pointer to it.
10void *realloc(void *ptr, size_t size)
Attempts to resize the memory block pointed to by ptr that was previously allocated with a call to malloc or calloc.
11void abort(void)
Causes an abnormal program termination.
12int atexit(void (*func)(void))
Causes the specified function func to be called when the program terminates normally.
13void exit(int status)
Causes the program to terminate normally.
14char *getenv(const char *name)
Searches for the environment string pointed to by name and returns the associated value to the string.
15int system(const char *string)
The command specified by string is passed to the host environment to be executed by the command processor.
16void *bsearch(const void *key, const void *base, size_t nitems, size_t size, int (*compar)(const void *, const void *))
Performs a binary search.
17void qsort(void *base, size_t nitems, size_t size, int (*compar)(const void *, const void*))
Sorts an array
18int abs(int x)
Returns the absolute value of x.
19div_t div(int numer, int denom)
Divides numer (numerator) by denom (denominator).
20long int labs(long int x)
Returns the absolute value of x.
21ldiv_t ldiv(long int numer, long int denom)
Divides numer (numerator) by denom (denominator).
22int rand(void)
Returns a pseudo-random number in the range of 0 to RAND_MAX.
23void srand(unsigned int seed)
This function seeds the random number generator used by the function rand.
24int mblen(const char *str, size_t n)
Returns the length of a multibyte character pointed to by the argument str.
25size_t mbstowcs(schar_t *pwcs, const char *str, size_t n)
Converts the string of multibyte characters pointed to by the argument str to the array pointed to by pwcs.
26int mbtowc(whcar_t *pwc, const char *str, size_t n)
Examines the multibyte character pointed to by the argument str.
27size_t wcstombs(char *str, const wchar_t *pwcs, size_t n)
Converts the codes stored in the array pwcs to multibyte characters and stores them in the string str.
28int wctomb(char *str, wchar_t wchar)
Examines the code which corresponds to a multibyte character given by the argument wchar.


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