C# Basics

Exception Handling

Validate operations and recover from expected failures.

Introduction

Exceptions separate normal control flow from exceptional failure handling.

TryParse is preferred for expected invalid input. try/catch is appropriate when an API reports failure through exceptions.

Runnable C# example

Run code →

Program.cs

using System;

class Program
{
    static void Main()
    {
        string input = "42";
        if (int.TryParse(input, out int value))
            Console.WriteLine(value * 2);
        else
            Console.WriteLine("Invalid number");
    }
}

Result of running the code

Practice with the debugger

Set a breakpoint on an important assignment or condition, click Debug, and inspect the local values before stepping to the next line.

Practice with a challenge

Use what this lesson covers to solve a real problem. Each challenge runs in your browser with instant tests and an AI review.

First Invalid Age Validate typed ages and report where the first bad entry is instead of letting the program crash. Easy
Sum the Valid Numbers Add up the entries that are whole numbers and skip everything else, the way try/except handles bad input. Easy

All challenges