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Go Switch

A switch statement is code that matches one value against a list of cases. The case with the matching value runs its statements.

Matching one case

The value 3 matches case 3. That case prints its day name.

package main

import "fmt"

func main() {
	day := 3
	switch day {
	case 1:
		fmt.Println("Monday")
	case 2:
		fmt.Println("Tuesday")
	case 3:
		fmt.Println("Wednesday")
	case 4:
		fmt.Println("Thursday")
	}
}

Sharing one case

Cases 6 and 7 share one case line. The value 6 matches that shared case.

package main

import "fmt"

func main() {
	day := 6
	switch day {
	case 6, 7:
		fmt.Println("Weekend")
	default:
		fmt.Println("Weekday")
	}
}

Falling through

The fallthrough statement carries the run into the next case. Both cases print a line.

package main

import "fmt"

func main() {
	n := 2
	switch n {
	case 2:
		fmt.Println("two")
		fallthrough
	case 3:
		fmt.Println("three")
	case 4:
		fmt.Println("four")
	}
}

A switch with no value

This switch names no value after the switch word. Each case holds a full condition instead.

package main

import "fmt"

func main() {
	score := 85
	switch {
	case score >= 90:
		fmt.Println("Band: A")
	case score >= 80:
		fmt.Println("Band: B")
	default:
		fmt.Println("Band: C")
	}
}

Example

package main

import "fmt"

func main() {
	grade := "B"
	switch grade {
	case "A":
		fmt.Println("Excellent")
	case "B":
		fmt.Println("Good")
	case "C":
		fmt.Println("Fair")
	default:
		fmt.Println("Try again")
	}
}

Key points

  • Each case names a value to match against the switch value.
  • A case can list more than one value, split by commas.
  • The default case runs when no case matches.
  • The fallthrough statement runs the next case as well.
  • A switch with no value after switch tests conditions in its cases.

In this example, grade holds the string B. The switch tests it against each case in order. Case B is the match, so its line prints. The printed line is "Good".

Note

A matched case ends on its own and does not run the next case.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Go Playground

Exercise

What does the fallthrough statement do?