rand（msdn）

/* RAND.C: This program seeds the random-number generator * with the time, then displays 10 random integers. */#include <stdlib.h>#include <stdio.h>#include <time.h>void main( void ){   int i;   /* Seed the random-number generator with current time so that    * the numbers will be different every time we run.    */   srand( (unsigned)time( NULL ) );   /* Display 10 numbers. */   for( i = 0;   i < 10;i++ )      printf( "  %6d\n", rand() );}

Output

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