Func<T, TResult> Delegate
Encapsulates a method that has one parameter and returns a value of the type specified by the TResult parameter.
Assembly: System.Core (in System.Core.dll)
The type of the parameter of the method that this delegate encapsulates.
The type of the return value of the method that this delegate encapsulates.
The parameter of the method that this delegate encapsulates.
The return value of the method that this delegate encapsulates.
You can use this delegate to represent a method that can be passed as a parameter without explicitly declaring a custom delegate. The method must correspond to the method signature that is defined by this delegate. This means that the encapsulated method must have one parameter that is passed to it by value and must return a value.
To reference a method that has one parameter and returns void (or in Visual Basic, that is declared as a Sub rather than as a Function), use the generic Action<T> delegate instead.
When you use the delegate, you do not have to explicitly define a delegate that encapsulates a method with a single parameter. For example, the following code explicitly declares a delegate named ConvertMethod and assigns a reference to the UppercaseString method to its delegate instance.
The following example simplifies this code by instantiating the delegate rather than explicitly defining a new delegate and assigning a named method to it.
You can also use the delegate with anonymous methods in C#, as the following example illustrates. (For an introduction to anonymous methods, see Anonymous Methods (C# Programming Guide).)
You can also assign a lambda expression to a delegate, as the following example illustrates. (For an introduction to lambda expressions, see Lambda Expressions and Lambda Expressions (C# Programming Guide).)
The underlying type of a lambda expression is one of the generic Func delegates. This makes it possible to pass a lambda expression as a parameter without explicitly assigning it to a delegate. In particular, because many methods of types in the System.Linq namespace have parameters, you can pass these methods a lambda expression without explicitly instantiating a delegate.
The following example demonstrates how to declare and use a delegate. This example declares a variable and assigns it a lambda expression that converts the characters in a string to uppercase. The delegate that encapsulates this method is subsequently passed to the Select method to change the strings in an array of strings to uppercase.
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.