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PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface
may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface
may not be implemented on Linux.
NAME
stdlib.h — standard library definitions
SYNOPSIS
#include <stdlib.h>
DESCRIPTION
Some of the functionality described on this reference page extends the ISO C standard. Applications shall
define the appropriate feature test macro (see the System Interfaces volume of POSIX.1‐2017, Section 2.2,
The Compilation Environment) to enable the visibility of these symbols in this header.
The <stdlib.h> header shall define the following macros which shall expand to integer constant
expressions:
EXIT_FAILURE
Unsuccessful termination for exit(); evaluates to a non-zero value.
EXIT_SUCCESS
Successful termination for exit(); evaluates to 0.
{RAND_MAX} Maximum value returned by rand(); at least 32767.
The <stdlib.h> header shall define the following macro which shall expand to a positive integer
expression with type size_t:
{MB_CUR_MAX}
Maximum number of bytes in a character specified by the current locale (category LC_CTYPE).
In the POSIX locale the value of {MB_CUR_MAX} shall be 1.
The <stdlib.h> header shall define NULL as described in <stddef.h>.
The <stdlib.h> header shall define the following data types through typedef:
div_t Structure type returned by the div() function.
ldiv_t Structure type returned by the ldiv() function.
lldiv_t Structure type returned by the lldiv() function.
size_t As described in <stddef.h>.
wchar_t As described in <stddef.h>.
In addition, the <stdlib.h> header shall define the following symbolic constants and macros as described
in <sys/wait.h>:
WEXITSTATUS
WIFEXITED
WIFSIGNALED
WIFSTOPPED
WNOHANG
WSTOPSIG
WTERMSIG
WUNTRACED
The following shall be declared as functions and may also be defined as macros. Function prototypes shall
be provided.
void _Exit(int);
long a64l(const char *);
void abort(void);
int abs(int);
int atexit(void (*)(void));
double atof(const char *);
int atoi(const char *);
long atol(const char *);
long long atoll(const char *);
void *bsearch(const void *, const void *, size_t, size_t,
int (*)(const void *, const void *));
void *calloc(size_t, size_t);
div_t div(int, int);
double drand48(void);
double erand48(unsigned short [3]);
void exit(int);
void free(void *);
char *getenv(const char *);
int getsubopt(char **, char *const *, char **);
int grantpt(int);
char *initstate(unsigned, char *, size_t);
long jrand48(unsigned short [3]);
char *l64a(long);
long labs(long);
void lcong48(unsigned short [7]);
ldiv_t ldiv(long, long);
long long llabs(long long);
lldiv_t lldiv(long long, long long);
long lrand48(void);
void *malloc(size_t);
int mblen(const char *, size_t);
size_t mbstowcs(wchar_t *restrict, const char *restrict, size_t);
int mbtowc(wchar_t *restrict, const char *restrict, size_t);
char *mkdtemp(char *);
int mkstemp(char *);
long mrand48(void);
long nrand48(unsigned short [3]);
int posix_memalign(void **, size_t, size_t);
int posix_openpt(int);
char *ptsname(int);
int putenv(char *);
void qsort(void *, size_t, size_t, int (*)(const void *,
const void *));
int rand(void);
int rand_r(unsigned *);
long random(void);
void *realloc(void *, size_t);
char *realpath(const char *restrict, char *restrict);
unsigned short *seed48(unsigned short [3]);
int setenv(const char *, const char *, int);
void setkey(const char *);
char *setstate(char *);
void srand(unsigned);
void srand48(long);
void srandom(unsigned);
double strtod(const char *restrict, char **restrict);
float strtof(const char *restrict, char **restrict);
long strtol(const char *restrict, char **restrict, int);
long double strtold(const char *restrict, char **restrict);
long long strtoll(const char *restrict, char **restrict, int);
unsigned long strtoul(const char *restrict, char **restrict, int);
unsigned long long
strtoull(const char *restrict, char **restrict, int);
int system(const char *);
int unlockpt(int);
int unsetenv(const char *);
size_t wcstombs(char *restrict, const wchar_t *restrict, size_t);
int wctomb(char *, wchar_t);
Inclusion of the <stdlib.h> header may also make visible all symbols from <stddef.h>, <limits.h>,
<math.h>, and <sys/wait.h>.
The following sections are informative.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
<limits.h>, <math.h>, <stddef.h>, <sys_types.h>, <sys_wait.h>
The System Interfaces volume of POSIX.1‐2017, Section 2.2, The Compilation Environment, _Exit(), a64l(),
abort(), abs(), atexit(), atof(), atoi(), atol(), bsearch(), calloc(), div(), drand48(), exit(), free(),
getenv(), getsubopt(), grantpt(), initstate(), labs(), ldiv(), malloc(), mblen(), mbstowcs(), mbtowc(),
mkdtemp(), posix_memalign(), posix_openpt(), ptsname(), putenv(), qsort(), rand(), realloc(), realpath(),
setenv(), setkey(), strtod(), strtol(), strtoul(), system(), unlockpt(), unsetenv(), wcstombs(), wctomb()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original
IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced
during the conversion of the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .