Increment and decrement in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of increment in a loop

What is the output of this Go program?

package main
import "fmt"
func main() {
  x := 0
  for i := 0; i < 3; i++ {
    x++
  }
  fmt.Println(x)
}

Go

package main
import "fmt"
func main() {
  x := 0
  for i := 0; i < 3; i++ {
    x++
  }
  fmt.Println(x)
}

A 3

B 0

C 1

D Syntax error

💡 Hint

Think about how many times the loop runs and how x changes each time.

The loop runs 3 times, and each time x is increased by 1 using x++. So final x is 3.

❓ Predict Output

intermediate

Decrement operator effect

What will this Go program print?

package main
import "fmt"
func main() {
  y := 5
  y--
  fmt.Println(y)
}

Go

package main
import "fmt"
func main() {
  y := 5
  y--
  fmt.Println(y)
}

A 5

B 6

C 4

D Compilation error

💡 Hint

Decrement means subtracting one from the variable.

y starts at 5, then y-- subtracts 1, so y becomes 4.

❓ Predict Output

advanced

Increment in expression

What is the output of this Go code?

package main
import "fmt"
func main() {
  a := 1
  b := a++
  fmt.Println(a, b)
}

Go

package main
import "fmt"
func main() {
  a := 1
  b := a++
  fmt.Println(a, b)
}

A Compilation error

B 1 1

C 2 1

D 1 2

💡 Hint

Go does not support post-increment as an expression.

In Go, the increment operator ++ is a statement, not an expression. So 'b := a++' causes a compilation error.

❓ Predict Output

advanced

Decrement in a for loop

What does this Go program print?

package main
import "fmt"
func main() {
  count := 3
  for count > 0 {
    fmt.Print(count, " ")
    count--
  }
}

Go

package main
import "fmt"
func main() {
  count := 3
  for count > 0 {
    fmt.Print(count, " ")
    count--
  }
}

A Compilation error

B 3 2 1

C 3 3 3

D 1 2 3

💡 Hint

The loop runs while count is greater than zero and decreases count each time.

The loop prints count starting at 3, then 2, then 1, then stops when count is 0.

🧠 Conceptual

expert

Why Go disallows increment in expressions

Why does Go language not allow using increment (++) or decrement (--) operators inside expressions like 'b := a++'?

A Because Go does not support increment or decrement operators at all.

B Because Go requires ++ and -- to be used only with pointers.

C Because Go only allows ++ and -- inside function definitions, not in main.

D Because ++ and -- are statements, not expressions, to avoid confusion and side effects in expressions.

💡 Hint

Think about how Go treats ++ and -- differently from some other languages.

Go treats ++ and -- as statements to keep code clear and avoid subtle bugs from side effects in expressions.