#include <iostream>
#include <string>
using namespace std;
int main() {
string userString;
cout << "Enter a string: ";
cin >> userString;
userString[1] = 'G';
cout << "Modified string: " << userString << endl;
return 0;
}
the user is prompted to enter a string, which is stored in the userString variable. The second character of the string can be accessed and modified using the square bracket syntax, for example userString[1] = 'G'. The modified string is then output.