C语言中快速随机数生成功能

Question

I'm trying to make a random number generator that produces many new random numbers very quickly. I have tried srand(time(NULL)) but since I'm trying to generate many number quickly this won't work. Next I tried this:

int main()
{
    seed_plus=time(NULL);    
    int i;
    for (i=0; i<10;i++)
    {
        double R=ran(seed_plus);
        printf("%lf\n",R);
        seed_plus=seed_plus+1;
    }
}
double ran (int seed_plus)
{

    srand(seed_plus);
    double random_number = (double)random()/(double)RAND_MAX;
    return(random_number);
}

This works, but I would like to have "seed_plus=seed_plus+1" contained within the "ran" function. When I move that statement inside the function I get many of the same "random" number, which leads me to believe that seed_plus is not being saved to memory since it is not the value being returned by the function?

I'm pretty new to C, so any help would be appreciated!

Answer 1

您只需要一次呼叫srand ，之后，所有对random下一次呼叫将每次返回不同的号码。

Answer 2

There is no reason to seed the random number generator every time you need a random number. Just simplify your code:

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

double ran(void)
{
    return (double)rand() / RAND_MAX;
}

int main(void)
{
    srand(time(NULL));
    for (int i = 0; i < 10; i++)
        printf("%f\n", ran());
}