在本教程中，您将学习如何使用switch-case语句根据Golang中的不同条件执行不同的操作。

Golang 还支持类似于其他语言（如Php或Java）中的 switch 语句。switch 语句是一种替代方法，用于根据变量的状态将冗长的 if else 比较表达为更具可读性的代码。

 

switch语句

switch语句用于选择要执行的多个代码块之一。

请考虑以下示例，该示例显示特定日期的不同消息。

package main
 
import (
	"fmt"
	"time"
)
 
func main() {
	today := time.Now()
 
	switch today.Day() {
	case 5:
		fmt.Println("Today is 5th. Clean your house.")
	case 10:
		fmt.Println("Today is 10th. Buy some wine.")
	case 15:
		fmt.Println("Today is 15th. Visit a doctor.")
	case 25:
		fmt.Println("Today is 25th. Buy some food.")
	case 31:
		fmt.Println("Party tonight.")
	default:
		fmt.Println("No information available for that day.")
	}
}

如果未找到匹配项，则使用default语句。

 

case拥有多个条件

case带有多个条件，用于为许多类似情况选择公共代码块。

package main
 
import (
	"fmt"
	"time"
)
 
func main() {
	today := time.Now()
	var t int = today.Day()
 
	switch t {
	case 5, 10, 15:
		fmt.Println("Clean your house.")
	case 25, 26, 27:
		fmt.Println("Buy some food.")
	case 31:
		fmt.Println("Party tonight.")
	default:
		fmt.Println("No information available for that day.")
	}
}

 

fallthrough关键字

fallthrough关键字，用于强制执行流通过连续的事例块。

package main
 
import (
	"fmt"
	"time"
)
 
func main() {
	today := time.Now()
 
	switch today.Day() {
	case 5:
		fmt.Println("Clean your house.")
		fallthrough
	case 10:
		fmt.Println("Buy some wine.")
		fallthrough
	case 15:
		fmt.Println("Visit a doctor.")
		fallthrough
	case 25:
		fmt.Println("Buy some food.")
		fallthrough
	case 31:
		fmt.Println("Party tonight.")
	default:
		fmt.Println("No information available for that day.")
	}
}

下面是每月 10 日的输出。

Buy some wine.
Visit a doctor.
Buy some food.
Party tonight.

 

有条件case

case语句还可以与条件运算符一起使用。

package main
 
import (
	"fmt"
	"time"
)
 
func main() {
	today := time.Now()
 
	switch {
	case today.Day() < 5:
		fmt.Println("Clean your house.")
	case today.Day() <= 10:
		fmt.Println("Buy some wine.")
	case today.Day() > 15:
		fmt.Println("Visit a doctor.")
	case today.Day() == 25:
		fmt.Println("Buy some food.")
	default:
		fmt.Println("No information available for that day.")
	}
}

 

switch初始值设定项语句

switch关键字可以紧跟一个简单的初始化语句，其中可以声明和初始化switch代码块的本地变量。

package main
 
import (
	"fmt"
	"time"
)
 
func main() {
	switch today := time.Now(); {
	case today.Day() < 5:
		fmt.Println("Clean your house.")
	case today.Day() <= 10:
		fmt.Println("Buy some wine.")
	case today.Day() > 15:
		fmt.Println("Visit a doctor.")
	case today.Day() == 25:
		fmt.Println("Buy some food.")
	default:
		fmt.Println("No information available for that day.")
	}
}