Exercices C#

Validate Input with TryParse

TryParse is a foundational C# pattern for converting untrusted text.

How it works

Parse user input without using exceptions for ordinary validation.

TryParse returns false and assigns the type's default value when conversion fails.

Runnable C# example

Program.cs

using System;
class Program
{
    static void Main()
    {
        foreach (string input in new[] { "42", "oops" })
            Console.WriteLine(int.TryParse(input, out int value) ? value * 2 : "Invalid");
    }
}

Expected output

84
Invalid

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.