[Author: @mdimamhosen Date: 2025-04-19 Category: e.g., interview-qa/topic_name Tags: [go, concurrency, channels] ]

The switch Statement

The switch statement allows us to execute one code block among many alternatives.

package main
import ("fmt")

func main() {
  day := 8

  switch 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")
  case 7:
    fmt.Println("Sunday")
  default:
    fmt.Println("Not a weekday")
  }
}

Frequently Asked Questions

1. What is a switch statement in Go?

Answer: A switch statement is used to select one of many code blocks to execute. It is an alternative to using multiple if-else statements.

Example:

package main
import "fmt"

func main() {
    num := 2
    switch num {
    case 1:
        fmt.Println("One")
    case 2:
        fmt.Println("Two")
    case 3:
        fmt.Println("Three")
    default:
        fmt.Println("Other number")
    }
}

2. Can we use multiple values in a single case?

Answer: Yes, multiple values can be grouped in a single case.

Example:

package main
import "fmt"

func main() {
    char := 'a'
    switch char {
    case 'a', 'e', 'i', 'o', 'u':
        fmt.Println("Vowel")
    default:
        fmt.Println("Consonant")
    }
}

3. Is break required in Go's switch statement?

Answer: No, break is not required as Go automatically breaks out of the switch after executing a case.

4. How to use fallthrough in a switch statement?

Answer: The fallthrough keyword forces the execution of the next case even if the condition does not match.

Example:

package main
import "fmt"

func main() {
    num := 1
    switch num {
    case 1:
        fmt.Println("One")
        fallthrough
    case 2:
        fmt.Println("Two")
    default:
        fmt.Println("Default")
    }
}

5. Can switch work without an expression?

Answer: Yes, a switch can work without an expression, making it similar to a series of if-else statements.

Example:

package main
import "fmt"

func main() {
    num := 10
    switch {
    case num < 0:
        fmt.Println("Negative")
    case num == 0:
        fmt.Println("Zero")
    case num > 0:
        fmt.Println("Positive")
    }
}

6. Can we use a switch statement with strings?

Answer: Yes, switch can be used with strings.

Example:

package main
import "fmt"

func main() {
    color := "red"
    switch color {
    case "red":
        fmt.Println("Stop")
    case "yellow":
        fmt.Println("Caution")
    case "green":
        fmt.Println("Go")
    default:
        fmt.Println("Unknown color")
    }
}

7. Can switch handle type assertions?

Answer: Yes, switch can be used to handle type assertions.

Example:

package main
import "fmt"

func main() {
    var x interface{} = 42
    switch v := x.(type) {
    case int:
        fmt.Printf("%d is an int\n", v)
    case string:
        fmt.Printf("%s is a string\n", v)
    default:
        fmt.Println("Unknown type")
    }
}

8. Can switch be used with functions?

Answer: Yes, you can use a function's return value in a switch statement.

Example:

package main
import "fmt"

func getNumber() int {
    return 3
}

func main() {
    switch getNumber() {
    case 1:
        fmt.Println("One")
    case 2:
        fmt.Println("Two")
    case 3:
        fmt.Println("Three")
    default:
        fmt.Println("Other number")
    }
}

9. Can switch be nested?

Answer: Yes, switch statements can be nested.

Example:

package main
import "fmt"

func main() {
    num := 2
    switch num {
    case 1:
        fmt.Println("One")
    case 2:
        fmt.Println("Two")
        switch num {
        case 2:
            fmt.Println("Nested switch")
        }
    default:
        fmt.Println("Other number")
    }
}

10. What happens if no case matches and there is no default?

Answer: If no case matches and there is no default, the switch statement does nothing.

Example:

package main
import "fmt"

func main() {
    num := 5
    switch num {
    case 1:
        fmt.Println("One")
    case 2:
        fmt.Println("Two")
    }
    // No output
}