Please help wity code. Why it doesn't work?

Question

#include <string>
using namespace std;

int main() {
string msg;
cin >> msg;
if(msg == "Hi"){
cout << "Hello";
}
return 0;
}

Answer 1

#include <iostream>
#include <string>
using namespace std;

int main() {
string msg;
getline(cin,msg);
if(msg == "Hi"){
cout << "Hello";
}
return 0;
}
getline()  function is used to store a stream of characters as entered by the user in the object memory.
so to access string element use like above

Answer 2

U forgot to include <iostream> which contains cin and cout and other few functions for input/output in the command-line