Func<t> and action<t> are different from the description

I. Func

Func is a. NET built-in delegate.

Func<result>,func<t1,result> is a. NET built-in generic delegates.

• Func<tresult>
• Func<t,tresult>
• Func<t1,t2,tresult>
• Func<t1,t2,t3,tresult>
• Func<t1,t2,t3,t4,tresult>

It has 5 forms, except that the number of parameters is different; the first one is no parameter, but there is a return value;

The following is an example of a simple generic delegate to pass a method.

        Private delegate string Say ();        public static string SayHello ()        {            return "Hello";        }        static void Main (string[] args)        {            Say Say = SayHello;            Console.WriteLine (Say ());            Console.readkey ();        }

So, at times, when we don't know what an interface is going to do at the same time, I can leave a delegate to it.

For more convenience,. NET has a delegate directly by default. Let's try it again. NET default with a delegate.

        public static string SayHello ()        {            return "Hello";        }        static void Main (string[] args)        {            func<string> say = SayHello;            Console.WriteLine (Say ());            Console.readkey ();        }

If you need a parameter, you can also send a copy of it.

        public static string SayHello (String str)        {            return str + str;        }        static void Main (string[] args)        {            func<string, string> say = SayHello;            String str = Say ("abc");                Console.WriteLine (str);     Output ABCABC            console.readkey ();        }

Second, Action

The use of action<t> is almost the same as Func, and the invocation method is similar.

• Action
• Action<t>
• Action<t1,t2>
• Action<t1,t2,t3>
• Action<t1,t2,t3,t4>

        Private delegate string Say ();        public static void SayHello (String str)        {            Console.WriteLine (str);        }        static void Main (string[] args)        {            action<string> say = SayHello;            Say ("abc");            Console.readkey ();        }

iii. The difference between Func and action

Func is almost the same as action. It's just that

• Func<result> has a return type;
• Action<t> only the parameter type, it cannot be passed the return type. So action<t> 's delegate function has no return value.

Iv. Func and action support the form of lambda invocation

Or, after one input, returns the value that repeats once as an example.

Func<string, string> say = m + = m + M;　　　　Console.WriteLine (Say ("abc")); Output ABCABC

Func<t> and action<t> are different from the description