题解 | #整数与IP地址间的转换# C++ 注意整数溢出

#include <iostream>
#include <bitset>
#include <sstream>
using namespace std;

int64_t ip_to_int(string ip) {

    stringstream ss(ip);

    string s;
    int64_t res = 0;

    // 183.31.75.22
    // 1675978389
    int rate = 24;
    while (getline(ss, s, '.')) {
        res |= (stoll(s) << rate);
        rate -= 8;
    }
    return res;
}

string int_to_ip(long long num) {
    string res;
    for (int i = 0; i < 3; ++i) {
        res =  "." + to_string(num % 256) + res;
        num >>= 8;
    }
    res = to_string(num) + res;
    return res;
}

int main() {
    string ip;
    long long num;
    while (cin >> ip >> num) {
         cout << ip_to_int(ip) << endl;
        cout << int_to_ip(num) << endl;
    }
    return 0;
}