使用C++时，将整数转换为始终具有3位数字的字符时会出现问题

#include <iostream>
#include <sstream>
#include <iomanip>

int main() {
    int num = 10;
    std::stringstream ss;
    ss << std::setw(3) << std::setfill('0') << num;
    std::string result = ss.str();
    std::cout << result << std::endl;
    return 0;
}

#include <iostream>
#include <string>

std::string convertToThreeDigits(int num) {
    std::string result;
    if (num < 10) {
        result = "00" + std::to_string(num);
    } else if (num < 100) {
        result = "0" + std::to_string(num);
    } else {
        result = std::to_string(num);
    }
    return result;
}

int main() {
    int num = 10;
    std::string result = convertToThreeDigits(num);
    std::cout << result << std::endl;
    return 0;
}