C/C++随机数生成的五种方法

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

int main() {
    srand(time(null));  // 初始化随机数生成器
    int random_number = rand() % 100;  // 生成 0 到 99 之间的随机数
    printf("random number: %d\n", random_number);
    return 0;
}

#include <random>
#include <iostream>

int main() {
    std::random_device rd;  // 真随机数生成器
    std::mt19937 gen(rd()); // mersenne twister 引擎
    std::uniform_int_distribution<> dis(0, 99);  // 生成 0 到 99 之间的整数

    int random_number = dis(gen);
    std::cout << "random number: " << random_number << std::endl;
    return 0;
}

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

int main() {
    file *file = fopen("/dev/urandom", "rb");
    unsigned char random_byte;
    if (fread(&random_byte, 1, 1, file) != 1) {
        perror("fread");
        exit(exit_failure);
    }
    fclose(file);

    int random_number = random_byte % 100;
    printf("random number: %d\n", random_number);
    return 0;
}

#include <x86intrin.h>
#include <stdio.h>

int main() {
    unsigned int random_number;
    _rdrand32_step(&random_number);  // 可能需要多次尝试才能成功
    printf("random number: %u\n", random_number % 100);
    return 0;
}

#include <openssl/rand.h>
#include <stdio.h>

int main() {
    unsigned char random_bytes[4];  // 生成 4 字节随机数
    if (!rand_bytes(random_bytes, sizeof(random_bytes))) {
        printf("rand_bytes failed\n");
        return 1;
    }

    unsigned int random_number = *(unsigned int *)random_bytes;
    printf("random number: %u\n", random_number % 100);
    return 0;
}