go入门二

package main

import (
    "io/ioutil"
    "fmt"
)

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

    //if也支持如下语法
    if content,err :=ioutil.ReadFile(filename);err !=nil{
        fmt.Println(err)
    }else{
        fmt.Printf("%s\n",content)
    }
}

package main

import "fmt"

//传入成绩，返回评分等级
func grade(score int) string {
    //定义字符串
    g := ""
    //go为switch每一句都加了break
    switch {
    case score < 0 || score > 100:
        g = "输入错误"
    case score < 60:
        g = "不及格"
    case score < 80:
        g = "良"
    case score < 90:
        g = "优"
    case score <= 100:
        g = "GOOD"
    }
    //default: "hahah"
    return g
}

func main(){
    fmt.Println(
        grade(0),
        grade(61),
        grade(75),
        grade(86),
        grade(86),
        grade(101),

    )
}