c# - What does it mean to call a function without being bound to an identifier -

i understand lambda expressions in sense of:

    delegate int del(int i);     static void main()     {         del mydelegate = x => x * x;         int j = mydelegate(2);         console.writeline(j);         console.readline();     } 

it's quite neat, , use again, read this:

    static void main()     {         thread t = new thread(() => print("hello t!"));         t.start();         console.readkey();     }      static void print(string message)     {         console.writeline(message);     } 

i can't quite figure out () => means, after googling found out (according wikipedia) using anonymous function undefinded (?) and/or not bound identifier.

now, ask mean? doing stated?

() => start of lambda expression doesn't have parameters. it's important understand lambda expression can't exist in vacuum - it's part of conversion either delegate type or expression tree type.

in case, being used argument thread constructor.

if @ thread constructor, there 4 overloads, 2 of have single parameter. 1 takes threadstart parameter, other takes parameterizedthreadstart parameter. these both delegate types, parameterizedthreadstart has parameter whereas threadstart doesn't.

so there's implicit conversion parameterless lambda expression threadstart, not parameterizedthreadstart, call overload taking threadstart.

so it's equivalent to:

threadstart tmp = () => print("hello t!"); thread t = new thread(tmp); 

to use parameterizedthreadstart, there 3 options:

// x inferred type object parameterizedthreadstart tmp = x => print("hello t!"); // same, brackets around parameter parameterizedthreadstart tmp = (x) => print("hello t!"); // explicit parameter list parameterizedthreadstart tmp = (object x) => print("hello t!"); 

(again, these inlined thread constructor call, , compiler infer constructor intended.)