Switch statement in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple switch statement

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")
  case 3:
    fmt.Println("Three")
  default:
    fmt.Println("Other")
  }
}

A Two

B Three

C One

D Other

💡 Hint

Look at the value of x and which case matches it.

The variable x is 2, so the switch matches case 2 and prints "Two".

❓ Predict Output

intermediate

Switch with multiple cases and fallthrough

What will this Go program print?

Go

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

A

One
Two
Three

B Two

C

One
Two

D One

💡 Hint

Remember that fallthrough makes the next case run too.

The switch matches case 1 and prints "One". The fallthrough causes case 2 to run next, printing "Two".

❓ Predict Output

advanced

Switch with expression and no matching case

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
  x := 10
  switch {
  case x < 5:
    fmt.Println("Less than 5")
  case x > 20:
    fmt.Println("Greater than 20")
  default:
    fmt.Println("Between 5 and 20")
  }
}

A Between 5 and 20

B Greater than 20

C Less than 5

D No output

💡 Hint

The switch has no expression, so it checks each case condition as a boolean.

x is 10, so x < 5 is false, x > 20 is false, so default runs printing "Between 5 and 20".

❓ Predict Output

advanced

Switch with type assertion

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)
  case string:
    fmt.Println("string", v)
  default:
    fmt.Println("unknown")
  }
}

A int 3

B float64 3.14

C unknown

D string 3.14

💡 Hint

The variable i holds a float64 value, so the type switch matches float64.

The type assertion switch matches float64 and prints "float64 3.14".

🧠 Conceptual

expert

Behavior of fallthrough in switch with multiple cases

Consider this Go code snippet: var x = 2 switch x { case 1, 2: fmt.Println("One or Two") fallthrough case 3: fmt.Println("Three") case 4: fmt.Println("Four") } What will be printed when this code runs?

A

One or Two
Three
Four

B One or Two

C Three

D

One or Two
Three

💡 Hint

fallthrough only moves to the next case, even if it has multiple values.

The switch matches case 1,2 and prints "One or Two". The fallthrough causes case 3 to run next, printing "Three". Case 4 does not run.

Practice

1. What does a switch statement do in Go?

easy

A. It selects one case to run based on a value.

B. It repeats code multiple times like a loop.

C. It defines a new function.

D. It declares a variable.

Solution

1. Step 1: Understand the purpose of switch

   A switch statement chooses one path among many based on a value.

2. Step 2: Compare with other options

   Loops repeat code, functions define behavior, variables store data. Switch picks cases.

3. Final Answer:

   It selects one case to run based on a value. -> Option A

4. Quick Check:

   Switch = Select case [OK]

Hint: Switch picks one matching case to run [OK]

Common Mistakes:

• Confusing switch with loops
• Thinking switch defines functions
• Believing switch declares variables

2. Which of the following is the correct syntax for a basic switch statement in Go?

easy

A. switch (x) { case 1: fmt.Println("One") default: fmt.Println("Other") }

B. switch x { case 1: fmt.Println("One") default: fmt.Println("Other") }

C. switch x: case 1: fmt.Println("One") default: fmt.Println("Other")

D. switch x { case 1 => fmt.Println("One") default => fmt.Println("Other") }

Solution

1. Step 1: Recall Go switch syntax

   Go uses switch variable { case value: ... default: ... } without parentheses.

2. Step 2: Check each option

   switch x { case 1: fmt.Println("One") default: fmt.Println("Other") } matches correct syntax. switch (x) { case 1: fmt.Println("One") default: fmt.Println("Other") } wrongly uses parentheses. switch x: case 1: fmt.Println("One") default: fmt.Println("Other") uses colon after switch. switch x { case 1 => fmt.Println("One") default => fmt.Println("Other") } uses => which is invalid.

3. Final Answer:

   switch x { case 1: fmt.Println("One") default: fmt.Println("Other") } -> Option B

4. Quick Check:

   Correct syntax = switch x { case 1: fmt.Println("One") default: fmt.Println("Other") } [OK]

Hint: No parentheses around switch variable in Go [OK]

Common Mistakes:

• Adding parentheses around switch variable
• Using colon after switch keyword
• Using => instead of colon in cases

3. What will be the output of this Go code?

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

medium

A. Two

B. Three

C. One

D. Other

Solution

1. Step 1: Identify the switch variable and value

   The variable x is 2.

2. Step 2: Match the case with value 2

   The case 2 matches and prints "Two".

3. Final Answer:

   Two -> Option A

4. Quick Check:

   Switch x=2 prints "Two" [OK]

Hint: Match switch value to case label [OK]

Common Mistakes:

• Choosing default instead of matching case
• Confusing case numbers
• Ignoring switch variable value

4. Find the error in this Go switch code:

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

medium

A. fmt.Println syntax error

B. Missing default case

C. Switch variable must be string

D. Missing colon after case 1

Solution

1. Step 1: Check case syntax

   Each case must end with a colon (:). Here, case 1 misses the colon.

2. Step 2: Verify other parts

   Default case exists, switch variable can be int, fmt.Println is correct.

3. Final Answer:

   Missing colon after case 1 -> Option D

4. Quick Check:

   Case syntax requires colon [OK]

Hint: Each case must end with a colon (:) [OK]

Common Mistakes:

• Omitting colon after case
• Thinking default is mandatory
• Assuming switch variable must be string

5. How can you write a Go switch statement that prints "Weekend" for Saturday and Sunday, and "Weekday" for other days (1=Monday, 7=Sunday)?

hard

A. switch day {
case day == 6 || day == 7:
fmt.Println("Weekend")
default:
fmt.Println("Weekday")
}

B. switch day {
case 6:
fmt.Println("Weekend")
case 7:
fmt.Println("Weekday")
default:
fmt.Println("Weekday")
}

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

D. switch day {
case 6:
fmt.Println("Weekend")
case 7:
fmt.Println("Sunday")
default:
fmt.Println("Weekday")
}

Solution

1. Step 1: Group weekend days in one case

   Using case 6, 7: groups Saturday and Sunday together.

2. Step 2: Use default for other days

   Default prints "Weekday" for days 1 to 5.

3. Final Answer:

   switch day { case 6, 7: fmt.Println("Weekend") default: fmt.Println("Weekday") } -> Option C

4. Quick Check:

   Multiple values in one case = switch day { case 6, 7: fmt.Println("Weekend") default: fmt.Println("Weekday") } [OK]

Hint: Use commas to group cases in Go switch [OK]

Common Mistakes:

• Separating weekend days into different cases with wrong output
• Using logical OR inside switch expression incorrectly
• Missing default case for weekdays