Switch expression behavior in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of switch with fallthrough

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    x := 2
    switch x {
    case 1:
        fmt.Println("One")
    case 2:
        fmt.Println("Two")
        fallthrough
    case 3:
        fmt.Println("Three")
    default:
        fmt.Println("Default")
    }
}

A Two\nThree

B Two

C Two\nDefault

D Three

💡 Hint

Remember that fallthrough causes the next case to run even if it doesn't match.

The switch matches case 2, prints "Two", then fallthrough causes case 3 to run, printing "Three".

❓ Predict Output

intermediate

Switch with multiple expressions

What will this Go program print?

Go

package main
import "fmt"
func main() {
    x := 5
    switch {
    case x < 0:
        fmt.Println("Negative")
    case x == 5:
        fmt.Println("Five")
    case x > 0:
        fmt.Println("Positive")
    default:
        fmt.Println("None")
    }
}

A Five

B Positive

C Negative

D None

💡 Hint

Switch without an expression evaluates cases as booleans in order.

The switch has no expression, so it checks each case condition. x == 5 is true, so it prints "Five" and stops.

❓ Predict Output

advanced

Switch with variable initialization and matching

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    switch x := 10; {
    case x < 5:
        fmt.Println("Less than 5")
    case x > 5:
        fmt.Println("Greater than 5")
    default:
        fmt.Println("Equal to 5")
    }
}

A Less than 5

B Equal to 5

C Greater than 5

D Compilation error

💡 Hint

The variable x is declared in the switch statement and used in case conditions.

x is 10, so x > 5 is true, printing "Greater than 5".

❓ Predict Output

advanced

Switch with type assertion and interface

What will this Go program print?

Go

package main
import "fmt"
func main() {
    var i interface{} = 3.14
    switch v := i.(type) {
    case int:
        fmt.Println("int", v)
    case float64:
        fmt.Println("float64", v)
    default:
        fmt.Println("unknown")
    }
}

A Compilation error

B int 3

C unknown

D float64 3.14

💡 Hint

Type switches check the dynamic type of an interface value.

i holds a float64 value 3.14, so the case float64 matches and prints "float64 3.14".

❓ Predict Output

expert

Switch with multiple expressions and fallthrough

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    x := 1
    switch x {
    case 1, 2:
        fmt.Println("One or Two")
        fallthrough
    case 3:
        fmt.Println("Three")
    case 4:
        fmt.Println("Four")
    default:
        fmt.Println("Default")
    }
}

A One or Two

B One or Two\nThree

C Three

D One or Two\nFour

💡 Hint

fallthrough passes control to the next case regardless of matching.

Case 1 matches, prints "One or Two", fallthrough causes case 3 to run, printing "Three".