基本语法• 和C语言同源的语法格式，有始有终的循环，for init; condition; post { }• 带条件的while循环，for condition { }• 无限循环，for { }有始有终的条件循环

sum := 0for i := 0; i < 10; i++ {    sum = sum + i}

注意：i变量在循环结束后无法使用

带条件的循环

count := 0for count < 10 {    fmt.Printf("Current count = %v\n", count)    count++}

由于循环不会停止，这里使用break来中断循环，后面还会详细介绍

 count := 0 for {     fmt.Printf("current count = %v\n", count)     count++     if count > 10 {         break     } }

类似C语言中的循环，我们可以通过计数器结合数组长度实现对数组的遍历，同时能获取数组索引，如下面例子所示

package mainimport "fmt"func main() {    myarray := []string{"a", "b", "c", "d"}    for i := 0; i < len(myarray); i++ {        fmt.Printf("Array index is %v, value is %v\n", i, myarray[i])    }}

利用range可以更容易的进行循环，并且range还能用于slice，channel和map的循环中

package mainimport "fmt"func main() {    myarray := []string{"a", "b", "c", "d"}    for index, item := range myarray {        fmt.Printf("current index is %v, value is %v\n", index, item)    }}

在介绍Map时，我们已经尝试用for循环对Map进行遍历，我们再来巩固一下

package mainimport "fmt"func main() {    mymap := map[int]string{1 : "a", 2 : "b", 3 : "c"}    for key, value := range mymap {        fmt.Printf("current key is %v, value is %v\n", key, value)    }}

如果只想获取key，则可以使用，省略value

for key := range mymap {

或者使用_，前面介绍过_无法用于变量，像个占位符

for _, value := range mymap {

下面的示例是对string类型的遍历，除了普通的字符，对于Unicode字符切分，字符通常是8位的，UTF-8的字符最高可能是32位的

package mainimport "fmt"func main() {    mystr := "abc"    for pos, char := range mystr {        fmt.Printf("character '%c' starts at byte position %d\n", char, pos)    }    for pos, char := range "Gő!" {        fmt.Printf("character '%c' starts at byte position %d\n", char, pos)    }}

character 'G' starts at byte position 0character 'ő' starts at byte position 1character '!' starts at byte position 3

与大部分语言一致

• Break结束当前循环• Continue开始下一次循环

package mainimport "fmt"func main() {    for i := 0; i < 10; i++ {        if i == 3 {            fmt.Printf("For continue at here: %d\n", i)            continue        }        if i > 5 {            fmt.Printf("For break at here: %d\n", i)            break        }        fmt.Printf("Current for count: %d\n", i)    }    fmt.Println("For loop end here")}

Current for count: 0Current for count: 1Current for count: 2For continue at here: 3Current for count: 4Current for count: 5For break at here: 6For loop end here

J:  for j := 0; j < 5; j++ {             for i := 0; i < 10; i++ {                 if i > 5 {                     break J                 }                 fmt.Println(i)             }         }