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

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     void
     srand(unsigned seed);

     void
     sranddev(void);

     int
     rand(void);

     int
     rand_r(unsigned *ctx);

DESCRIPTION
     These interfaces are obsoleted by random(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 ctx must be supplied by the caller.

     For better generator quality, use random(3) or lrand48(3).	 Applications
     requiring cryptographic quality randomness should use arc4random(3).

SEE ALSO
     arc4random(3), lrand48(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				October 6, 2010				   BSD
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