package main

import "fmt"

// function add

func add(a, b int) int { return a + b}

// 1

func testFunc1() {

// function "add" to var "f1"// then "f1" is a functionf1 := add// type of f1 = func(int int) intfmt.Printf("type of f1 = %T\n", f1)// call function "f1"// params are 2 and 5sum := f1(2, 5)// sum = 7fmt.Printf("sum = %d\n", sum)

}

// 2

func testFunc2() {

// anonymous function to var "f1", then "f1" is a functionf1 := func(a, b int) int {    return a + b}// type of f1 = function(int, int) intfmt.Printf("type of f1 = %T\n", f1)// call function f1, params are 2 and 5sum := f1(2, 5)// sum = 7fmt.Printf("sum = %d\n", sum)

}

// 3

func testFunc3() { var i = 0

// the statement after "defer" will be pushed into stack first// so the value of var "i" will be "0"// defer i = 0defer fmt.Printf("defer i = %d\n", i)i = 100// i = 100fmt.Printf("i = %d\n", i)return

}

// 4

func testFunc4() { var i = 0

// the anonymous function after "defer" will be pushed into stack first// but at this time, the statement in function will not be pushed into stack// so at this time the value of var "i" is not specific// the value of var// at the end the value of var "i" is 100defer func() {    fmt.Printf("defer i = %d\n", i)}()i = 100// i = 100fmt.Printf("i = %d\n", i)return

}

func main() {

//testFunc1()//testFunc2()//testFunc3()testFunc4()}