程序代码：

#include <stdio.h>
#include <stdlib.h>
#if _WIN32
#include <time.h>
#else
#include <sys/time.h>
#endif

int main()
{
    srand((unsigned int)time(NULL));
    for (int i = 0; i < 20; ++i)
    {
        printf("%d ", rand()%100);
        if ((i + 1)%5 == 0)
            printf("\n");
    }
    return 0;
}