C++ string.at() Out-of-Range Exception Example

The given C++ program demonstrates the use of the string.at() method and how to handle the out_of_range exception it can throw.

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

int main() {
  string s = 'Hello';
  try {
    s.at(5);
  } catch (out_of_range & e) {
    cerr << e.what() << endl;
  }
  return 0;
}

The program tries to access the character at index 5 in the string s, which is 'Hello'. Since the string has only 5 characters (indexed from 0 to 4), this causes an out_of_range exception.

The catch block handles the exception, and the code prints the error message generated by the exception, which is:

'basic_string::at: __n (which is 5) >= this->size() (which is 5)'

This message indicates that the attempted access at index 5 is out of bounds because the string's size is 5. The program then continues execution normally.