随机密码

#include 
#include 
#include 

#define CHAR_SMALL_CASE 0
#define CHAR_UPPER_CASE 1
#define CHAR_DIGIT 2
#define CHAR_SPECIAL 3

const char c_small_case[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
                             'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};

const char c_upper_case[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
                             'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};

const char c_digit[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

const char c_special[] = {'!', '@', '#', '$', '%', '^', '&', '*', '(', ')'}; // 还可以再加点特殊字符

// 密码生成器
// @param buf[out] 输出生成的密码
// @param buf_len[in] 输出区长度
// @param code_len[in] 产生密码的长度
// @param contain_special[in] 密码是否包含特殊字符
// return 0 on failuer, code_len on success
int code_generator(char *buf, int buf_len, int code_len, int contain_special);

int main(int argc, char *argv[])
{
    char code[256];
    int code_len = 128; // 要求密码长度为128
    int len = code_generator(code, sizeof(code), code_len, 1);

    if (len == code_len)
    {
        printf("%s\n", code);
    }
    getchar();
    return 0;
}

int code_generator(char *buf, int buf_len, int code_len, int contain_special)
{
    if (buf_len + 1 < code_len) // 输出去长度判读
    {
        return 0;
    }

    srand(time(NULL)); // 随机数

    int i;
    for(i = 0; i < code_len; ++i)
    {
        int char_type = rand()%4;
        switch(char_type)
        {
        case CHAR_SMALL_CASE:
            *buf = c_small_case[rand() % sizeof(c_small_case)];
            break;
        case CHAR_UPPER_CASE:
            *buf = c_upper_case[rand() % sizeof(c_upper_case)];
            break;
        case CHAR_DIGIT:
            *buf = c_digit[rand() % sizeof(c_digit)];
            break;
        case CHAR_SPECIAL:
            if (!contain_special) // 跳过特殊字符
            {
                --i;
                continue;
            }
            *buf = c_special[rand() % sizeof(c_special)];
            break;
        default:
            break;
        }
        ++buf;
    }
    *buf = '\0'; // 以'\0'结束
    return code_len;
}