The throw Keyword

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The throw Keyword

The throw Keyword

throw raises an exception explicitly, either a new one or an existing caught exception being rethrown. Rethrowing with plain throw; inside a catch block preserves the original stack trace, while throw ex; resets it. Methods that detect invalid input or state typically throw rather than return an error code.

Warning: Prefer throw; over throw ex; when rethrowing, so debugging tools show where the error actually originated.

Example: The throw Keyword

markup

using System;

class Program
{
    static void CheckAge(int age)
    {
        if (age < 0)
            throw new ArgumentException("Age cannot be negative");
        Console.WriteLine($"Age {age} is valid");
    }

    static void Main(string[] args)
    {
        try
        {
            CheckAge(-5);
        }
        catch (ArgumentException ex)
        {
            Console.WriteLine("Error: " + ex.Message);
        }
    }
}

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The throw Keyword

The throw Keyword

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