rand（）问题在C编程？ [英] rand() issue in C programming?

问题描述

可能重复：

所以是的，这可能看起来有点noobish，但因为我教自己C在Java后变得合理，我已经运行进入一些麻烦。我试图在C中使用rand（）函数，但我只能调用一次，当它做，它总是生成相同的随机数，这是41.我使用的是Microsoft Visual C ++ 2010 Express，我已经设置它所以它会编译C代码，但唯一不工作的是这个rand（）函数。我试过包括一些通用的库，但没有什么工作。以下是代码：

So yeah, this might seem slightly noobish, but since I'm teaching myself C after becoming reasonable at Java, I've already run into some trouble. I'm trying to use the rand() function in C, but I can only call it once, and when it do, it ALWAYS generates the same random number, which is 41. I'm using Microsoft Visual C++ 2010 Express, and I already set it up so it would compile C code, but the only thing not working is this rand() function. I've tried including some generally used libraries, but nothing works. Here's the code:

#include "stdafx.h"
#include "stdio.h"
#include "conio.h"
#include "stdlib.h"

int main(void)
{
    printf("%d", rand()); //Always prints 41

    return 0;
}

推荐答案

$ c> rand（）始终从执行开始时的同一点初始化其伪随机序列。

This because the rand() initializes its pseudo-random sequence always from the same point when the execution begins.

随机种子，然后使用 rand（）获取不同的值。这可以通过函数 srand 来完成，这将根据所传递的种子移动序列。

You have to input a really random seed before using rand() to obtain different values. This can be done through function srand that will shift the sequence according to the seed passed .

尝试： / p>

Try with:

srand(clock());   /* seconds since program start */
srand(time(NULL));   /* seconds since 1 Jan 1970 */

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