一.if語句
if語句條件中定義變量是屬于局部變量，只有對應的if中的條件和執(zhí)行語句中有效。
if x > 10 {
fmt.Println("x is greater than 10")
} else {
fmt.Println("x is less than 10")
}
// 計算獲取值x,然后根據(jù)x返回的大小，判斷是否大于10。
if x := computedValue(); x > 10 {
fmt.Println("x is greater than 10")
} else {
fmt.Println("x is less than 10")
}
//這個地方如果這樣調(diào)用就編譯出錯了，因為x是條件里面的變量
fmt.Println(x)
if integer == 3 {
fmt.Println("The integer is equal to 3")
} else if integer < 3 {
fmt.Println("The integer is less than 3")
} else {
fmt.Println("The integer is greater than 3")
}
二.循環(huán)語句for
//無限循環(huán) 必須要break跳出
a:=1
for{
a++
if a >= 3 {
break
}
}
sum := 1
for sum < 1000 {
sum += sum
}
sum := 1
for ; sum < 1000; {
sum += sum
}
for index := 10; index>0; index-- {
if index == 5{
break // 或者continue
}
fmt.Println(index)
}
// break打印出來10、9、8、7、6
// continue打印出來10、9、8、7、6、4、3、2、1
for配合range可以用于讀取slice和map的數(shù)據(jù)：
for k,v:=range map {
fmt.Println("map's key:",k)
fmt.Println("map's val:",v)
}
由于 Go 支持 “多值返回”, 而對于“聲明而未被調(diào)用”的變量, 編譯器會報錯, 在這種情況下, 可以使用_來丟棄不需要的返回值 例如
for _, v := range map{
fmt.Println("map's val:", v)
}
三.switch語句-其實默認每個case最后面都有一個break
switch sExpr {
case expr1:
some instructions
case expr2:
some other instructions
case expr3:
some other instructions
default:
other code
}
i := 10
switch i {
case 1://這里可以帶條件 和if的條件一樣
fmt.Println("i is equal to 1")
case 2, 3, 4:
fmt.Println("i is equal to 2, 3 or 4")
case 10:
fmt.Println("i is equal to 10")
default:
fmt.Println("All I know is that i is an integer")
}
integer := 6
switch integer {
case 4:
fmt.Println("The integer was <= 4")
fallthrough/這個一加后面的case語句都會繼續(xù)判斷和執(zhí)行 相當于取消了break/
case 5:
fmt.Println("The integer was <= 5")
fallthrough
case 6:
fmt.Println("The integer was <= 6")
fallthrough
case 7:
fmt.Println("The integer was <= 7")
fallthrough
case 8:
fmt.Println("The integer was <= 8")
fallthrough
default:
fmt.Println("default case")
}
四.goto break continue
