十六进制转十进制

hex_to_dec.cpp

#include <iostream>
#include <cmath>

using namespace std;

void hex_to_dec(string &hex) {
    long long dec = 0;
    for (int i = hex.length() - 1; i >= 0; i--) {
        int num = 0;
        if (hex[i] >= '0' && hex[i] <= '9') {
            num = hex[i] - 48;
        } else {
            num = hex[i] - 55;
        }
        dec += num * pow(16, hex.length() - i - 1);
    }
    cout << dec << endl;
}

int main() {
    string s;
    cin >> s;
    hex_to_dec(s);
    return 0;
}