In C#, What is <T> After a Method Declaration?

Answer 1

This defines a generic method, which is one form of generics, which were added to C# in C# 2.0.

The method sig should be:

static void Foo<T>(params T[] x)
{ // ...

This lets you pass any number of arguments of any (specific) type into the method Foo, and it acts on that array of arguments. It's similar to how generic types work, except scoped just to the method. The <T> specifies the type of the argument being passed into the method, so you can call this like:

Foo<MyClass>(myClassInstance, myClassInstance2, mySubclassInstance);

Answer 2

That is the Generic Type parameter of a Generic Method.

Once you specify a type for T when calling the method, .NET can ensure type safety based on that type parameter.

static void Foo<T>(params T[] x) { }

would be called like:

string[] names = new string[] {"Foo", "Bar", "Baz"};

Foo<string>(names);

but this would cause a compiler error:

int[] nums = new int[] {1, 2, 3};

Foo<string>(nums); // nums is not string[]

Answer 3

The T is a type parameter and in this case can be anything (a constraint may be specified, but here there is no constraint). Without this feature you would have to declare the method for every type you plan to use:

static void Foo(params int[] x)    
static void Foo(params string[] x)    
static void Foo(params Customer[] x)    
etc...

More information on generics can be found on MSDN: Introduction to Generics (C#).

Answer 4

what you are asking is the concept of the generics in c#. By using generics you can use this method for the types you want

suppose you have to create function to add two number in that cause your function is

//For integer :
public int sum(int a,int b)
{ 
  return a+ b;
}



//For floating point numbers :
public float sum( float a, float b)
{
  return a + b;
}

and if you have to add to double you create one more function .

Bu with the help of generics you have to create only one function

public T sum<T>(T a, T b)
{
  return a + b;
}

This will work for int, float , double of the numeric also for the string.

check this out for more detail : http://www.codeproject.com/kb/books/EssentialCS20.aspx