Handling errors in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if an error occurred after opening a file.

Go

file, err := os.Open("test.txt")
if [1] != nil {
    fmt.Println("Error opening file")
}

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

Aos

Bfile

Cnil

Derr

Attempts:

3 left

💡 Hint

Common Mistakes

Checking 'file' instead of 'err' for errors.

Comparing 'err' to a value other than nil.

The variable 'err' holds the error returned by os.Open. We check if 'err' is not nil to detect an error.

2fill in blank

medium

Complete the code to return an error from a function.

Go

func divide(a, b int) (int, error) {
    if b == 0 {
        return 0, [1].New("division by zero")
    }
    return a / b, nil
}

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

Amath

Berrors

Cfmt

Dos

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fmt.New' instead of 'errors.New'.

Returning nil instead of an error when b is zero.

The 'errors' package provides the New function to create a new error value.

3fill in blank

hard

Fix the error in the code to handle the error returned by strconv.Atoi.

Go

num, [1] := strconv.Atoi("123a")
if err != nil {
    fmt.Println("Conversion error")
}

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

Aerr

Berror

Cnum

DconvErr

Attempts:

3 left

💡 Hint

Common Mistakes

Naming the error variable differently than 'err'.

Not checking the error after conversion.

The error variable must be named 'err' to match the check in the if statement.

4fill in blank

hard

Fill both blanks to handle an error returned by ioutil.ReadFile.

Go

data, [1] := ioutil.ReadFile("file.txt")
if [2] != nil {
    fmt.Println("Failed to read file")
}

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

Aerr

Bdata

Dfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for the error.

Checking the wrong variable for errors.

The error variable is named 'err' and must be checked for nil to detect errors.

5fill in blank

hard

Fill all three blanks to create and check a custom error using fmt.Errorf.

Go

func checkAge(age int) error {
    if age < 18 {
        return [1].Errorf("age %d is too young", [2])
    }
    return [3]
}

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

Afmt

Bage

Cnil

Derrors

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'errors.New' without formatting.

Returning an error when age is valid.

Use 'fmt.Errorf' to create a formatted error, pass 'age' as argument, and return nil if no error.