First go program

1. stay GO In language , All independently running programs must include package main, And all go The document must be marked with package <name> start

2. Use import Import required library files . As in the example code fmt

An example of variables and formatted output ：

package main

import (
	"fmt"
)

func main() {
	var a int    //define int var a, defalt 0
	var b string //define string var b defalt ""
	fmt.Printf("a = %d\n", a)
	fmt.Printf("b = %s\n", b)
	c := 10   //define int var c with value 10
	d := true //define bool var d with value true
	fmt.Printf("c = %d\n", c)
	if d {
		fmt.Println("d is true,so we get here.")
	}
	e, f := 20, 16 //also we can define two var in one line
	fmt.Printf("e = %d\n", e)
	fmt.Printf("f = %d\n", f)
	//define const enum var
	const (
		g = iota //0
		h = iota //1
	)
	fmt.Printf("g = %d\n", g)
	fmt.Printf("h = %d\n", h)
	s := `Charles'
	first GO program!`
	/*	//same with following code
		s := "Charles" +
			"first GO program!"*/

	fmt.Println(s)
	//var i int  /* if defined a var, and never use it, there will be a error*/

	hello := "hello"
	Arr := []byte(hello) // convert hello to a byte array
	Arr[0] = 'c'
	s2 := string(Arr)
	fmt.Printf("%s\n", s2)
}