Synopsis
#include <stdlib.h>
int rand(void);
int rand_r(unsigned *seed);
void srand(unsigned seed);
Status
Partially implemented
Conformance
IEEE Std 1003.1-2017
Description
The rand() function shall compute a sequence of pseudo-random integers in the range [0, RAND_MA] with a
period of at least 232.
The
rand() function need not be thread-safe.
The rand_r() function shall compute a sequence of pseudo-random integers in the range [0, RAND_MA]. (The value of
the RAND_MA macro shall be at least 32767.)
If rand_r() is called with the same initial value for the object pointed to by seed and that object is not
modified between successive returns and calls to rand_r(), the same sequence shall be generated.
The srand() function uses the argument as a seed for a new sequence of pseudo-random numbers to be returned by subsequent
calls to rand(). If srand() is then called with the same seed value, the sequence of pseudo-random numbers shall be
repeated. If rand() is called before any calls to srand() are made, the same sequence shall be generated as when
srand() is first called with a seed value of 1.
The implementation shall behave as if no function defined in this volume of POSIX.1-2017 calls rand() or
srand().
Return value
The rand() function shall return the next pseudo-random number in the sequence.
The rand_r() function shall return a pseudo-random integer.
The srand() function shall not return a value.
Errors
No errors are defined.
Tests
Untested
Known bugs
None