运算符>>读取int十六进制和十进制？

#include<iostream>
#include <iomanip>

int main() {
    int hex_value;
    std::cout << "Enter a hexadecimal number: ";
    std::cin >> std::hex >> hex_value;

    std::cout << "Decimal value: "<< std::dec<< hex_value<< std::endl;
    return 0;
}

#include<iostream>
#include <iomanip>

int main() {
    int dec_value = 255;
    std::cout << "Hexadecimal value: "<< std::hex<< dec_value<< std::endl;
    return 0;
}