go 내장 방법len,cap,close

지원되는 유형:
len:string,array,slice,map,chan
cap:slice,array,chan
close:chan

package main

import "fmt"

func main(){
	//getLen()
	closeChan()
}
//       
func getLen(){
	mIDMap := make([]string,3,6) //make         
	mIDMap[0]="id-1"
	mIDMap[1]="id-2"
	mIDMap[2]="id-3"
	fmt.Println("mIDMap len ",len(mIDMap)) //   mIDMap len  3
	fmt.Println("mIDMap cap ",cap(mIDMap)) //   mIDMap len  3

}
//     chan
func closeChan(){
	mChan := make(chan int,1)
	mChan