　　　　　　　Functions also refer to "methods".

Normal Functions

　　Defining / Using / Returning values

static <returnType> <FunctionName>() => <returnValue>;

// expression-bodied functions

　　Parameters

　　　　Matching in order

　　　　Parameter array

 1 static <returnType> <FunctionName>(<p1Type> <p1Name>, ..., params <type> [] <name>) 
 2  {
 3 
 4   ...
 5  
 6   return <returnValue>;
 7  
 8 }
 9 
10 /* the same as fellowing:
11 <FunctionName>(<p1>, ..., <val1>, <val2>, ...)<val1>, <val2>,
12 and so on are values of type <type>, which are used to initialize the <name>array
13 */

　　Reference and Value Parameters

　　　　3 Types of Reference

in	specifies that this parameter is passed by reference but is only read by the called method
ref	specifies that this parameter is passed by reference and may be read or written by the called method(must be signed)
out	specifies that this parameter is passed by reference and is written by the called method (created by called function, treated as an unsigned parameter)

Variables like strings and arrays are reference types and arrays can be returned with the ref keyword without a parameter declaration.

　　Tuple

　　　　　　It's designed for returning multiple values from the functions and most used when a program does not need a struct or more complicated implementations.

　　Parameters and Return Values vs. Global Data

Other Functions

　　Local Functions

　　　　　　Local functions allow you to declare a function within the context of another function.

　　　　　　It can't be called from other functions contained in the class where the former function is defined.

　　Structure Functions

　　Overloading Functions

　　　　　　To provide a uniform function model for various kinds of inputs to achieve a particular purpose.

　　Delegate

　　　　　　storage of reference of functions

1 //define a delegate
2 delegate <a define of function>; // now we have the delegate's name : <delegateName>
3 //use a delegate
4 <delegateName> <delegateVariableName>;
5 <delegateVariableName> = <FunctionName>; // this function is of the delegate's type
6 //now this <delegateVariableName> can be used as a "function" of its type

Chapter 6 Functions