stdlib.h - standard library definitions
stdlib.h is a C library header file. It is also availible in C++, though there are some minor changes.
This header file defines the following macro names:
EXIT_FAILURE
Unsuccessful termination for exit(), evaluates to a non-zero value.
EXIT_SUCCESS
Successful termination for exit(), evaluates to 0.
NULL
Null pointer.
RAND_MAX
Maximum value returned by rand(), at least 32,767.
MB_CUR_MAX
Integer expression whose value is the maximum number of bytes in a character specified by the current locale.

The following data types are defined through typedef:
div_t
Structure type returned by div() function.
ldiv_t
Structure type returned by ldiv() function.
size_t
As described in <stddef.h>.
wchar_t
As described in <stddef.h>.

In addition, the following symbolic names and macros are defined as in , for use in decoding the return value from system():
WNOHANG
WUNTRACED
WEXITSTATUS()
WIFEXITED()
WIFSIGNALED()
WIFSTOPPED()
WSTOPSIG()
WTERMSIG()

The following are declared as functions and may also be defined as macros. Function prototypes must be provided for use with an ISO C compiler.
long a64l(const char *);
convert between a a radix-64 ASCII string and a 32-bit integer
void abort(void);
generate an abnormal process abort
int abs(int);
return an integer absolute value
int atexit(void (*)(void));
register a function to run at process termination
double atof(const char *);
convert a string to double-precision number
int atoi(const char *);
convert a string to integer
long atol(const char *);
convert a string to long integer
void *bsearch(const void *, const void *, size_t, size_t, int (*)(const void *, const void *));
binary search a sorted table
void *calloc(size_t, size_t);
allocates memory and zeros it
div_t div(int, int);
compute the quotient and remainder of an integer division
double drand48(void);
return non-negative, double-precision, floating-point values, uniformly distributed over the interval 0.0 , 1.0
char *ecvt(double, int, int *, int *);
convert a floating-point number to a string
double erand48(unsigned short[3]);
return non-negative, double-precision, floating-point values, uniformly distributed over the interval 0.0 , 1.0
void exit(int);
terminate a process
char *fcvt (double, int, int *, int *);
convert a floating-point number to a string
void free(void *);
free allocated memory
char *gcvt(double, int, char *);
convert a floating-point number to a string
char *getenv(const char *);
get value of an environment variable
int getsubopt(char **, char *const *, char **);
parse suboption arguments from a string
int grantpt(int);
grant access to the slave pseudo-terminal device
char *initstate(unsigned int, char *, size_t);
pseudorandom number functions
long int jrand48(unsigned short[3]);
generate a uniformly distributed pseudo-random long signed integer
char *l64a(long);
convert a 32-bit integer to a radix-64 ASCII string
long int labs(long);
return a long integer absolute value
void lcong48(unsigned short[7]);
seed a uniformly distributed pseudo-random signed long integer generator
ldiv_t ldiv(long, long);
compute quotient and remainder of a long division
long lrand48(void);
generate uniformly distributed pseudo-random non-negative long integers
void *malloc(size_t);
a memory allocator
int mblen(const char *, size_t);
get number of bytes in a character
size_t mbstowcs(wchar_t *, const char *, size_t);
convert a character string to a wide-character string
int mbtowc(wchar_t *, const char *, size_t);
convert a character to a wide-character code
char *mktemp(char *);
make a unique filename
int mkstemp(char *);
make a unique file name
long mrand48(void);
generate uniformly distributed pseudo-random signed long integers
long nrand48(unsigned short int [3]);
generate uniformly distributed pseudo-random non-negative long integers
char *ptsname(int);
get name of the slave pseudo-terminal device
int putenv(char *);
change or add a value to environment
void qsort(void *, size_t, size_t, int (*)(const void *, const void *));
quick sort a table of data
int rand(void);
pseudo-random number generator
int rand_r(unsigned int *);
pseudo-random number generator
long random(void);
generate pseudorandom number
void *realloc(void *, size_t);
memory reallocator
char *realpath(const char *, char *);
resolve a pathname
unsigned short seed48(unsigned short[3]);
seed uniformly distributed pseudo-random non-negative long integer generator
void setkey(const char *);
set encoding key
char *setstate(const char *);
switch pseudorandom number generator state arrays
void srand(unsigned int);
seed simple pseudo-random number generator
void srand48(long int);
seed uniformly distributed double-precision pseudo-random number generator
void srandom(unsigned);
seed pseudorandom number generator
double strtod(const char *, char **);
convert string to a double-precision number
long strtol(const char *, char **, int);
convert string to a long integer
unsigned long strtoul(const char *, char **, int);
convert string to an unsigned long
int system(const char *);
issue a command
int ttyslot(void); (LEGACY)
find the slot of the current user in the user accounting database
int unlockpt(int);
unlock a pseudo-terminal master/slave pair
void *valloc(size_t); (LEGACY)
page-aligned memory allocator
size_t wcstombs(char *, const wchar_t *, size_t);
convert a wide-character string to a character string
int wctomb(char *, wchar_t);
convert a wide-character code to a character

Inclusion of the header may also make visible all symbols from <stddef.h>, <limits.h>, <math.h> and <sys/wait.h>.

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