Go语言基础（五）条件语句

if条件语句

package main

import (
	"fmt"
	"io/ioutil"
)

func main() {
	const filename = "abc.txt"
	contents,err :=ioutil.ReadFile(filename)
	if err == nil {
		fmt.Println(err)
	}else {
		fmt.Printf("%s\n",contents)
	}
}

运行结果如下：

创建一个abc.txt文件在执行

运行结果如下：

go语言的if可以像其他语言的for一样编写

func main() {
	const filename = "abc.txt"
	if contents,err :=ioutil.ReadFile(filename); err != nil{
		fmt.Println(err)
	}else {
		fmt.Printf("%s\n",contents)
	}
}

switch条件语句

switch会自动break，除非使用fallthrough，switch后面可以没有表达式

package main

import (
	"fmt"
)

func grade(score int) string {
	g :=""
	switch  {
	case score < 0 || score > 100:
		panic(fmt.Sprintf("Wrong Score: %d",score))
	case score < 60:
		g = "F"
	case score < 80:
		g = "C"
	case score < 90:
		g = "B"
	case score <= 100:
		g = "A"
	}
	return g
}

func main() {
	fmt.Println(
		grade(0),
		grade(55),
		grade(60),
		grade(88),
		grade(95),
		grade(100),
		grade(120),
		)
}

运行结果如下：