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Top Forums Programming Generating Random Number in Child Process using Fork Post 302597471 by Corona688 on Friday 10th of February 2012 11:42:56 AM
Old 02-10-2012
If you put the same seed in, you get the same numbers out.

time() only changes once a second. How long does your program take to run? Less than a second?

That's why I suggested putting the PID into it as well. That changes every single time...
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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 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
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