go if for while using

fileName := "a.txt"
contents ,err := ioutil.ReadFile(fileName)
    if err != nil{
       fmt.Println("文件不存在")
 }else{
   fmt.Printf("%s\n",contents)
 }

fileName := "a.txt"
if contents ,err := ioutil.ReadFile(fileName);err!=nil{

 fmt.Println ( "file does not exist")

}else{

 fmt.Printf("%s\n",contents)

} 

Switch default language will go plus break

C 2 = var 
Switch C { 
Case. 1: 
   fmt.Print (C) 
Case 2: 
   fmt.Print ( "Hello") 
Case. 3: 
   fmt.Print ( "World") 
default: 
    fmt.Println ( "the this IS The End" ) 

behind the switch can not follow the expression 

var score = 80

 switch {
 case score >90 :
   fmt.Print(score)
 case score >80:
   fmt.Print("hello")
 case score >70:
   fmt.Print("world")
 default:
    fmt.Println("this is the end")