Lesson 16 of 20Practical Modern C++22 min

Exception Handling

Exceptions separate normal program logic from error-handling logic. A function can throw an exception, and a caller can handle it inside a catch block.

Throwing and Catching an Exception

Safe division

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

double divide(double numerator, double denominator)
{
    if (denominator == 0)
        throw invalid_argument("Denominator cannot be zero.");

    return numerator / denominator;
}

int main()
{
    try
    {
        cout << divide(10, 0) << endl;
    }
    catch (const exception& error)
    {
        cout << "Error: " << error.what() << endl;
    }

    return 0;
}

Exception Flow

Code runs normally inside try.
A problem causes an exception to be thrown.
Control moves to a matching catch block.
The program can report the problem or recover safely.

Use exceptions thoughtfully

Exceptions are appropriate for exceptional failures, not as a replacement for ordinary conditions such as a normal menu choice.

Practice task

Write a function that throws out_of_range when a mark is below 0 or above 100.

Lesson Summary

Respond to runtime problems using try, throw, catch, and standard exceptions.