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Contract::Requires<TException> Method (Boolean, String)

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

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

generic<typename TException>
where TException : Exception 
static void Requires(
	bool condition, 
	String^ userMessage

Type Parameters


The exception to throw if the condition is false.


Type: System::Boolean

The conditional expression to test.

Type: System::String

The message to display if the condition is false.

  • Important noteImportant

    You must turn on run-time checking to use the Requires 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, String) method when you want to throw an exception if the precondition fails.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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