Contract.Requires<TException> Method (Boolean)


Specifies a precondition contract for the enclosing method or property, and throws an exception if the condition for the contract fails.

Namespace:   System.Diagnostics.Contracts
Assembly:  mscorlib (in mscorlib.dll)

public static void Requires<TException>(
	bool condition
where TException : Exception


Type: System.Boolean

The conditional expression to test.

Type Parameters


The exception to throw if the condition is false.


You must turn on run-time checking to use the Requires<TException> method. If run-time checking is turned off, the process will be terminated. To obtain the tools for runtime checking, see Code Contracts on the MSDN DevLabs Web site.

  • This method call must be at the beginning of a method or property, before any other code.

  • This contract is exposed to clients; therefore, it must only reference members that are at least as visible as the enclosing method.

  • Use this method instead of the Contract.Requires(Boolean) method when you want to throw an exception if the precondition fails.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 4.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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