C# · Original teaching example

C#: validate numeric input

CodeVideoNote · Updated 2026-10-04

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Problem

A text field must become a number without throwing on invalid input.

Approach and limits

TryParse reports success and assigns the parsed value. Handle failure explicitly instead of silently using zero.

Example code

if (int.TryParse(input, out int count))
{
    Console.WriteLine(count);
}
else
{
    Console.WriteLine("Enter a whole number.");
}

Check it yourself

Input 12 should print 12; input twelve should show the validation message.