Go Switch Statements
The switch statement is a shorter way of writing an if-else statement. It allows you to execute one among many code blocks based on a condition. It runs the first case where the expression matches the value.
The Go switch statement is similar to the switch statements in other programming languages such as C#, C++, and java.
In Go, the switch statements can have a single case or multiple case values for each case.
In single value switch statements, each case will have a single value to be compared with the expression, as shown in the following example.
switch expression {
case 1:
//code block 1
case 2:
//code block 2
case 3:
//code block 3
default:
//default code block
}
In the above syntax, the expression is evaluated once. Its value is compared with the value of each case. When the expression value matches the case value, the code block of that case is executed. If none of the cases matches the expression then the default code block is executed.
In the following example, the month is passed as a number and the case displays the actual month in words.
package main
import "fmt"
func main() {
thisMonth := 5
switch thisMonth {
case 1:
fmt.Println("January")
case 2:
fmt.Println("February")
case 3:
fmt.Println("March")
case 4:
fmt.Println("April")
case 5:
fmt.Println("May")
case 6:
fmt.Println("June")
}
}
May
The following example contains multiple values in each case.
package main
import "fmt"
func main() {
thisMonth := 6
switch thisMonth {
case 1, 3, 5, 7, 8, 10,12:
fmt.Println("31 days")
case 4,6,9,11:
fmt.Println("30 days")
case 2:
fmt.Println("28 days")
}
}
30 days
The switch statements can be used with any datatype.
package main
import "fmt"
func main() {
thisMonth := "May"
switch thisMonth {
case "January":
fmt.Println("1")
case "February":
fmt.Println("2")
case "March":
fmt.Println("3")
case "April":
fmt.Println("4")
case "May":
fmt.Println("5")
case "June":
fmt.Println("6")
}
}
5
Conditional Case
The comparison operators can be used in the switch case statements, as shown below.
package main
import "fmt"
func main() {
x := 20
y := 10
switch {
case x > y:
fmt.Println("x is greater than y")
case x < y:
fmt.Println("x is less than y")
default:
fmt.Println("x is equal to y")
}
}
x is greater than y
Fallthrough Case Statement
The fallthrough keyword in the case statement transfers the execution to the next case.
package main
import "fmt"
func main() {
x := 3
switch x {
case 1:
fmt.Println("1")
fallthrough
case 3:
fmt.Println("3")
fallthrough
case 5:
fmt.Println("5")
}
}
3
5
Go Switch Initializer Statement
Like for loop and if statement, the switch statement can start with the short statement. For example, a variable local to the switch block can be declared and initialized immediately after the switch keyword, as shown below.
package main
import "fmt"
func main() {
switch day:= 4; day {
case 1:
fmt.Println("Monday")
case 2:
fmt.Println("Tuesday")
case 3:
fmt.Println("Wednesday")
case 4:
fmt.Println("Thursday")
case 5:
fmt.Println("Friday")
case 6:
fmt.Println("Saturday")
default:
fmt.Println("Sunday")
}
}
Thursday
In the above example, a variable day is declared and initialized immediately after the switch keyword. It is also passed as the expression to the switch block. It is local to the switch block where it is declared.
