C++生成任意字符串

C++语言，生成任意字符串的函数

void  Downloader::generate(char * buff, int name_len)

{
    char metachar[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    srand(time(NULL));
    for (int i = 0; i < name_len - 1; i++)
    {
//匹配metachar中的任意字符
        buff[i] = metachar[rand() % 62]; 
    }
    buff[name_len - 1] = '\0';
}