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throw (C# Reference)

The throw statement is used to signal the occurrence of an anomalous situation (exception) during the program execution.

The thrown exception is an object whose class is derived from System.Exception, for example:

class MyException : System.Exception {}
// ...
throw new MyException();

Usually the throw statement is used with try-catch or try-finally statements. When an exception is thrown, the program looks for the catch statement that handles this exception.

You can also rethrow a caught exception using the throw statement. For more information and examples, see try-catch and Throwing Exceptions.

This example demonstrates how to throw an exception using the throw statement.

// throw example
using System;
public class ThrowTest 
    static void Main() 
        string s = null;

        if (s == null) 
            throw new ArgumentNullException();

        Console.Write("The string s is null"); // not executed

The ArgumentNullException exception occurs.

For more information, see the following sections in the C# Language Specification:

  • Throw statements

  • 8.9.5 The throw statement