C#
===

## List
1. [absract class](#AC)
2. [IEnumrator](#IE)
3. [out](#out)
4. [Invoke](#invoke)

## Contents
### abstract class<a id="AC"/>
<i>**abstract class**</i> is inheritable class. Like java's Interface.
1. virtual / override
- Overide function must be declared `virtual`.

        [abstract]
        public virtual void func();
        
        [inheritance]
        public override void func();

2. abstract function
- `Abstract function` only have name. Inheritance class must declare this function, if not, occuer *<b>Error</b>*

       abstract void function();

### IEnumerator<a id="IE"/>
Like JS's generator, yield values sequentially. It is called **<i>Coroutine</i>** in C#.

IEnumerator func() {
    yield return 1;
    yield return 2;
    yield return 3;
}

func(); //=> 1
func(); //=> 2
func(); //=> 3;

It use for subroutine no relation with `Update()`.<br>Update is called every frame. But frame don't work correct time duration.<br>So we use `Coroutine` for smooth moving, etc...

### out<a id="out"/>
`out` is like reference value in C, C++. If you want change outside scope value change in scope, use this modifier with parameter.

void func(out int a);

int a;
func(out a);

**※** Smillar modifier `ref`. It must initiate first.

### Invoke<a id="Invoke"/>
`Invoke()` is multi threading work function.<br>In unity, function for delay. It smillar `setTimeOut()` in JS, but It work correct after delay time, unlike `setTimeOut()`.