#1,173 – Lambda Expression Can Be Just an Expression

You’ll often see lambda expressions written as either a single statement (no return value) or a block of statements (optional return value).

        static void SomeMethod(int i, string s)
        {
            // do something with int and string
        }

        static void Main(string[] args)
        {
            // Single statement
            Action<int, string> thing1 = (i, s) => SomeMethod(i, s);

            // Block of statements, no return value
            Action<int, string> thing2 = (i, s) =>
            {
                for (int i2 = i; i2 <= i + 10; i2++)
                    SomeMethod(i2, s);
            };

            // Block of statements with return value
            Func<int,int> thing3 = (i) =>
            {
                SomeMethod(i, "x");
                return i + 1;
            };
        }

A lambda expression can also be a single statement representing an expression whose type is assignment compatible with the return value of the delegate type being assigned to.

            // Expression
            Func<int, int> doubleMe = (i) => 2 * i;
            Console.WriteLine(doubleMe(42));