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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 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, suitable for crypto-graphic cryptographic graphic 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 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 |