Go语言文件基础语法

package main //管理定义模块
import "fmt" //导入模块
/*
主函数
打印Hello,world!
*/
func main() {
	fmt.Println("Hello,world!")
}

var变量

3种变量声明方式:

package main
import "fmt"
func main() {
	var a string
	a = "a"
	var b = "b"
	c := "c"
	var(
		d string
		e = "e"
	)
	d = "d"
	fmt.Println(a, b, c, d, e)
}

const常量

iota实现枚举

package main
import "fmt"
func main() {
	const a = "a"
	const b = 1
	const (
		c = iota
		d
		e
	)
	const (
		f = (iota + 1) * 2 // iota每次const均重置
		g
		h
	)
	fmt.Println(a, b, c, d, e, f, g, h) //a 1 0 1 2 2 4 6
}

if判断与for循环

判断与多种循环的方法

package main
import (
	"fmt"
	"time"
)
func main() {
	for i := 0; i < 4; i++ {
		if i < 1 {
			j := 0
			for ; j < 3; j++ {
				fmt.Print(j) //012
			}
		} else if i == 1 {
			j := 1
			for j < 4 {
				fmt.Print(j) //123
				j++
			}
		} else if i == 2 {
			for k, v := range "abc" {
				fmt.Printf("%d %c,", k, v) //0 a,1 b,2 c,
			}
		} else {
			for {
				time.Sleep(1000000000) // 等待若干纳秒(1000000000纳秒=1秒)
				fmt.Println("死循环")
			}
		}
	}
}

基本数据类型

package main
import "fmt"
func main() {
	var (
		// 整型
		// 无符号整型
		a uint8  = 1
		b uint16 = 2
		c uint32 = 3
		d uint64 = 4
		// 有符号整型
		e int8  = -1
		f int16 = -2
		g int32 = -3
		h int64 = -4
		//uint和int是32位还是64位具体看操作系统
		i uint = 0
		j      = 1          //Go语言默认为int
		k      = uintptr(2) //指针
		//浮点型
		l         = 0.123 //Go语言默认为float64
		m float32 = 0.234
		//复数
		n complex64 = complex(1, 2)
		o           = complex(3, 4) //Go语言默认为complex128
		p           = "abc"         //字符串string
		q           = 0777          //八进制
		r           = 0xff          //十六进制
	)
	//布尔值bool:true和false
	fmt.Println(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, true, false)
	fmt.Printf("%T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T, %T", a, b, c, d, e,
		f, g, h, i, j, k, l, m, n, o, p, q, r, true, false)
}