Panic behavior in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to cause a panic with the message "error occurred".

Go

func main() {
    panic([1])
}

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A"error occurred"

Berror occurred

Cpanic("error occurred")

Dfmt.Println("error occurred")

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the string message

Calling panic inside panic argument

Using print functions instead of panic

The panic function takes a value to display as the panic message. It must be a string literal here.

2fill in blank

medium

Complete the code to recover from a panic inside the deferred function.

Go

func main() {
    defer func() {
        if r := [1](); r != nil {
            println("Recovered from panic")
        }
    }()
    panic("fail")
}

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Arecover

Bclose

Cdefer

Dpanic

Attempts:

3 left

💡 Hint

Common Mistakes

Using panic instead of recover

Calling recover outside a deferred function

Not checking if recover returned nil

The recover function is used inside a deferred function to catch a panic and prevent the program from crashing.

3fill in blank

hard

Fix the error in the code to properly recover from a panic and print the panic message.

Go

func main() {
    defer func() {
        if r := [1](); r != nil {
            println("Panic message:", r)
        }
    }()
    panic("something went wrong")
}

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Afmt.Println

Brecover

Cpanic

Dclose

Attempts:

3 left

💡 Hint

Common Mistakes

Using panic instead of recover

Trying to recover outside defer

Not checking if recover returned nil

Using recover() inside a deferred function allows catching the panic and accessing its message.

4fill in blank

hard

Fill both blanks to create a map of strings to their lengths, but only include words longer than 3 characters.

Go

func main() {
    words := []string{"go", "code", "panic", "fun"}
    lengths := map[string]int{
        [1]: len([2]) for _, word := range words if len(word) > 3
    }
    fmt.Println(lengths)
}

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Aword

Bwords

Clen(word)

Dword.len

Attempts:

3 left

💡 Hint

Common Mistakes

Using the whole slice as key or value

Trying to call len as a method

Using wrong variable names

We use word as the key and len(word) as the value for each word longer than 3 characters.

Note: Go does not support map comprehensions like this; this is a conceptual exercise.

5fill in blank

hard

Fill all three blanks to create a deferred function that recovers from panic and prints the panic message.

Go

func main() {
    defer func() {
        if r := [1](); r != nil {
            fmt.[2]("Recovered panic: %v", [3])
        }
    }()
    panic("unexpected error")
}

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Apanic

Brecover

Cr

DPrintf

Attempts:

3 left

💡 Hint

Common Mistakes

Using panic instead of recover

Using fmt.Println instead of fmt.Printf

Not passing the recovered value to print

Use recover() to catch the panic, fmt.Printf to print formatted output, and r as the recovered panic message.