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RAND(3)                  BSD Library Functions Manual                  RAND(3)

NAME
     rand, rand_r, srand, sranddev -- bad random number generator

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     int
     rand(void);

     int
     rand_r(unsigned *seed);

     void
     srand(unsigned seed);

     void
     sranddev(void);

DESCRIPTION
     These interfaces are obsoleted by arc4random(3).

     The rand() function computes a sequence of pseudo-random integers in the range of 0 to RAND_MAX (as
     defined by the header file <stdlib.h>).

     The srand() function sets its argument seed as the seed for a new sequence of pseudo-random numbers to
     be returned by rand().  These sequences are repeatable by calling srand() with the same seed value.

     If no seed value is provided, the functions are automatically seeded with a value of 1.

     The sranddev() function initializes a seed, using the random(4) random number device which returns good
     random numbers.  However, the rand() function still remains unsuitable for cryptographic use.

     The rand_r() function provides the same functionality as rand().  A pointer to the context value seed
     must be supplied by the caller.

SEE ALSO
     arc4random(3), random(3), random(4)

STANDARDS
     The rand() and srand() functions conform to ISO/IEC 9899:1990 (``ISO C90'').

     The rand_r() function is as proposed in the POSIX.4a Draft #6 document.

BSD                              May 25, 1999                              BSD

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