如何在 C++ 中创建一个随机的字母数字字符串?

2021-12-21 00:00:00 string random c++

我想创建一个随机字符串，由字母数字字符组成.我希望能够指定字符串的长度.

I'd like to create a random string, consisting of alpha-numeric characters. I want to be able to be specify the length of the string.

我如何在 C++ 中做到这一点?

How do I do this in C++?

推荐答案

Mehrdad Afshari 的 answer 可以解决问题，但我发现它对于这个简单的任务来说有点过于冗长.查找表有时可以创造奇迹:

Mehrdad Afshari's answer would do the trick, but I found it a bit too verbose for this simple task. Look-up tables can sometimes do wonders:

#include <ctime>
#include <iostream>
#include <unistd.h>

std::string gen_random(const int len) {
    static const char alphanum[] =
        "0123456789"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz";
    std::string tmp_s;
    tmp_s.reserve(len);

    for (int i = 0; i < len; ++i) {
        tmp_s += alphanum[rand() % (sizeof(alphanum) - 1)];
    }
    
    return tmp_s;
}

int main(int argc, char *argv[]) {
    srand((unsigned)time(NULL) * getpid());     
    std::cout << gen_random(12) << "
";        
    return 0;
}

请注意，rand 生成质量较差的随机数.

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