// example from https://en.cppreference.com/w/cpp/string/basic_string/at
//
#include <stdexcept>
#include <iostream>
#include <string>

// added this and removed std:: throughout, RP:
//
using namespace std;
 
int main()
{
    string s("message"); // for capacity
 
    s = "abc";
    s.at(2) = 'x'; // ok
    cout << s << '\n';
 
    cout << "string size = " << s.size() << '\n';
    cout << "string capacity = " << s.capacity() << '\n';
 
    try {
        // throw, even if capacity allowed to access element
        s.at(3) = 'x';
    }
    // catch (out_of_range const& exc) {
    // simplified catch, RP:
    //
    catch (const exception& exc) {
        cout << exc.what() << '\n';
    }
}