A brief introduction to C# Lambda expressions

Lambda expressions can be seen as a quick way to define functions or delegates. It has the following two forms:

(input-parameters) => expression

(input-parameters) => { <sequence-of-statements> }

Here are two examples

Func<int, int> square = x => x * x;
Console.WriteLine(square(5));
// Output:
// 25

Action<string> greet = name =>
{
    string greeting = $"Hello {name}!";
    Console.WriteLine(greeting);
};
greet("World");
// Output:
// Hello World!

In the first example, the two ints after func respectively represent the input parameter type and the return value type, square is the method name, x is the formal parameter, and x*x is the return value.

In the second example, the string behind Action indicates the input type, greet is the function name, and name is the formal parameter.