Output using fmt.Println in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of fmt.Println with multiple arguments

What is the output of this Go code snippet?

Go

package main
import "fmt"
func main() {
    fmt.Println("Hello", "World", 2024)
}

A HelloWorld2024

B Hello World 2024

C "Hello World 2024"

D Hello, World, 2024

💡 Hint

fmt.Println separates arguments with spaces by default.

fmt.Println prints each argument separated by a space and adds a newline at the end.

❓ Predict Output

intermediate

Output of fmt.Println with newline characters

What will this Go program print?

Go

package main
import "fmt"
func main() {
    fmt.Println("Line1\nLine2")
}

A

Line1
Line2

B Line1\nLine2

C Line1 Line2

D Line1\n Line2

💡 Hint

The string contains an escape sequence for newline.

The \n inside the string creates a new line when printed by fmt.Println.

❓ Predict Output

advanced

Output of fmt.Println with slice argument

What is the output of this Go code?

Go

package main
import "fmt"
func main() {
    nums := []int{1, 2, 3}
    fmt.Println(nums)
}

A 1,2,3

B 1 2 3

C [1 2 3]

D []int{1, 2, 3}

💡 Hint

fmt.Println prints slices with brackets and spaces.

fmt.Println prints slices in a format with square brackets and spaces between elements.

❓ Predict Output

advanced

Output of fmt.Println with pointer variable

What will this Go program print?

Go

package main
import "fmt"
func main() {
    x := 10
    p := &x
    fmt.Println(p)
}

A &10

B 10

C p

D 0xc0000140b0

💡 Hint

Printing a pointer shows its memory address.

fmt.Println prints the memory address stored in the pointer variable.

❓ Predict Output

expert

Output of fmt.Println with interface and type assertion

What is the output of this Go code?

Go

package main
import "fmt"
func main() {
    var i interface{} = 42
    fmt.Println(i)
    if v, ok := i.(int); ok {
        fmt.Println(v * 2)
    }
}

A

42
84

B

42
42

C

interface value
84

D

42
<nil>

💡 Hint

Type assertion extracts the int value from interface{}.

The interface holds 42, printing it shows 42, then doubling prints 84.