GO语言-基础语法：条件判断

1. IF判断(aa.txt内容：asdfgh。bb.txt内容：12345)

package mainimport ("io/ioutil""fmt"
)func main() {const filename1, filename2 = "aa.txt", "bb.txt"contents, err := ioutil.ReadFile(filename1) if err != nil {fmt.Println(err)} else{fmt.Printf("%s\n", contents)}fmt.Printf("%s\n", contents) //打印出filename1的内容if contents, err := ioutil.ReadFile(filename2);err != nil {fmt.Println(err)} else {fmt.Printf("%s\n", contents)}fmt.Printf("%s\n", contents) //还是打印出filename1的内容，filename2在if条件内，跳出IF之后失效（IP内部赋值，只对本次IF有效）
}

打印结果;

asdfgh
asdfgh
12345
asdfgh
[Finished in 0.6s]

2. switch

package mainimport ("fmt"
)//定义函数：grade：函数名。score：传入的变量，类型是int。string：函数返回的类型。
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"default://在本次switch中可以不写default，因为第一个case已经判断了所以的异常
         panic(fmt.Sprintf("Wrong score: %d", score))}return g
}func main() {fmt.Println(grade(50),grade(60),grade(90),grade(10))
}