Extension methods for chaining C# with Example

When an extension method returns a value that has the same type as its this argument, it can be used to "chain" 
one or more method calls with a compatible signature. This can be useful for sealed and/or primitive types, and 
allows the creation of so-called "fluent" APIs if the method names read like natural human language. 
void Main() 
{ 
int result = 5.Increment().Decrement().Increment(); 
// result is now 6 
} 
public static class IntExtensions 
{ 
public static int Increment(this int number) { 
return ++number; 
} 
public static int Decrement(this int number) { 
return --number; 
} 
} 
 

Or like this 
void Main() 
{ 
int[] ints = new[] { 1, 2, 3, 4, 5, 6}; 
int[] a = ints.WhereEven(); 
//a is { 2, 4, 6 }; 
int[] b = ints.WhereEven().WhereGreaterThan(2); 
//b is { 4, 6 }; 
} 
public static class IntArrayExtensions 
{ 
public static int[] WhereEven(this int[] array) 
{ 
//Enumerable.* extension methods use a fluent approach 
return array.Where(i => (i%2) == 0).ToArray(); 
} 
public static int[] WhereGreaterThan(this int[] array, int value) 
{ 
return array.Where(i => i > value).ToArray(); 
} 
}