Go语言的 break label 和 continue label | Konica 的自留地

Go语言的 break label 和 continue label

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Fantasy, Landscape, Mountains, Human, Wanderer

标号 label

for循环中break和continue只是针对最近的一重循环，但在多重循环中，可以用标号label标出想break或continue的循环。
规定标号label必须放在for循环之前，即label必须紧跟循环, 否则出现 invalid continue label 错误

示例

仔细观察a1~a4四个函数代码和程序运行结果，看看有什么不同。

Go语言代码

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package main
import "fmt"
func main() {
	a1()
	a2()
	a3()
	a4()
}
func a1() {
	fmt.Println("---- func a1() continue with label: ")
re:
	for i := 1; i <= 3; i++ {
		fmt.Printf("i: %d\n", i)
		for i2 := 11; i2 <= 13; i2++ {
			fmt.Printf("i2: %d\n", i2)
			continue re
		}
	}
}
func a2() {
	fmt.Println("---- func a2() continue without label: ")
	for i := 1; i <= 3; i++ {
		fmt.Printf("i: %d\n", i)
		for i2 := 11; i2 <= 13; i2++ {
			fmt.Printf("i2: %d\n", i2)
			continue
		}
	}
}
func a3() {
	fmt.Println("---- func a3() break with label: ")
re:
	for i := 1; i <= 3; i++ {
		fmt.Printf("i: %d\n", i)
		for i2 := 11; i2 <= 13; i2++ {
			fmt.Printf("i2: %d\n", i2)
			break re
		}
	}
}
func a4() {
	fmt.Println("---- func a4() break without label: ")
	for i := 1; i <= 3; i++ {
		fmt.Printf("i: %d\n", i)
		for i2 := 11; i2 <= 13; i2++ {
			fmt.Printf("i2: %d\n", i2)
			break
		}
	}
}

运行结果

---- func a1() continue with label:
i: 1
i2: 11
i: 2
i2: 11
i: 3
i2: 11
---- func a2() continue without label:
i: 1
i2: 11
i2: 12
i2: 13
i: 2
i2: 11
i2: 12
i2: 13
i: 3
i2: 11
i2: 12
i2: 13
---- func a3() break with label:
i: 1
i2: 11
---- func a4() break without label:
i: 1
i2: 11
i: 2
i2: 11
i: 3
i2: 11