Defer execution order in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to defer printing "First".

Go

package main
import "fmt"
func main() {
    [1] fmt.Println("First")
    fmt.Println("Second")
}

Drag options to blanks, or click blank then click option'

Ago

Bdefer

Cfunc

Dprint

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'go' instead of 'defer' causes the function to run concurrently.

Forgetting 'defer' causes immediate execution.

The defer keyword delays the execution of the function until the surrounding function returns.

2fill in blank

medium

Complete the code to print "Third" last using defer.

Go

package main
import "fmt"
func main() {
    defer fmt.Println("[1]")
    fmt.Println("First")
    fmt.Println("Second")
}

Drag options to blanks, or click blank then click option'

AThird

BFirst

CSecond

DLast

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'First' or 'Second' will print them immediately, not deferred.

Using 'Last' is not the exact string to print.

The deferred call prints "Third" after the other prints because defer delays execution until the function ends.

3fill in blank

hard

Fix the error in the defer statement to print "Done" last.

Go

package main
import "fmt"
func main() {
    defer fmt.Println([1])
    fmt.Println("Start")
}

Drag options to blanks, or click blank then click option'

Adone

BDone

C"Done"

D'Done'

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted Done causes a compile error.

Using single quotes 'Done' is invalid for strings.

Strings in Go must be enclosed in double quotes. Using "Done" correctly passes a string literal.

4fill in blank

hard

Fill both blanks to defer two prints so "Second" prints before "First".

Go

package main
import "fmt"
func main() {
    defer fmt.Println([1])
    defer fmt.Println([2])
    fmt.Println("Start")
}

Drag options to blanks, or click blank then click option'

A"First"

B"Start"

C"Second"

D"End"

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the strings will print in the wrong order.

Using unrelated strings confuses the output order.

Deferred calls run in last-in-first-out order. The second defer prints "Second" before the first defer prints "First".

5fill in blank

hard

Fill all three blanks to defer prints so output order is: Start, Third, Second, First.

Go

package main
import "fmt"
func main() {
    fmt.Println("Start")
    defer fmt.Println([1])
    defer fmt.Println([2])
    defer fmt.Println([3])
}

Drag options to blanks, or click blank then click option'

A"Start"

B"First"

C"Second"

D"Third"

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing the order of deferred prints changes output order.

Not quoting strings causes compile errors.

The immediate print shows "Start" first. Deferred prints run in reverse order: last defer prints "Third", then the middle defer prints "Second", then the first defer prints "First".