Return values in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the sum of two integers.

Go

func add(a int, b int) int {
    return a [1] b
}

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

Forgetting to return the result.

The function should return the sum of a and b. The + operator adds two numbers.

2fill in blank

medium

Complete the code to return the length of a string.

Go

func length(s string) int {
    return [1](s)
}

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

Alength

Bsize

Clen

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent functions like size or count.

Trying to access string length as a property.

The built-in len function returns the length of a string in Go.

3fill in blank

hard

Fix the error in the function to return the product of two floats.

Go

func multiply(x float64, y float64) float64 {
    return x [1] y
}

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

A+

B*

C/

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or division instead of multiplication.

Syntax errors by missing operator.

The function should return the product, so the multiplication operator * is needed.

4fill in blank

hard

Fill both blanks to return a map with words as keys and their lengths as values, only for words longer than 3 characters.

Go

func wordLengths(words []string) map[string]int {
    lengths := make(map[string]int)
    for _, word := range words {
        if [1](word) [2] 3 {
            lengths[word] = [1](word)
        }
    }
    return lengths
}

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

Alen

B>

C<

Dcap

Attempts:

3 left

💡 Hint

Common Mistakes

Using cap instead of len.

Using < instead of >.

Not calling len as a function.

The function uses len(word) to get the length of each word and checks if it is greater than 3 using >.

5fill in blank

hard

Fill all three blanks to return a new map with uppercase keys and values only for entries with values greater than 10.

Go

func filterAndUppercase(data map[string]int) map[string]int {
    result := make(map[string]int)
    for [1], [2] := range data {
        if [2] [3] 10 {
            result[strings.ToUpper([1])] = [2]
        }
    }
    return result
}

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

AToUpper

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up key and value variable names.

Using wrong comparison operators.

Forgetting to call ToUpper as a function.

The loop uses k and v for key and value. It checks if v > 10 and adds the uppercase key using strings.ToUpper().

Practice

1. What does a function's return value in Go do?

easy

A. It defines the function's name.

B. It comments the code for documentation.

C. It declares variables inside the function.

D. It sends a result back to the place where the function was called.

Solution

1. Step 1: Understand the purpose of return values

   Return values are used to send results from a function back to the caller.

2. Step 2: Identify the correct description

   Only It sends a result back to the place where the function was called. correctly describes this purpose.

3. Final Answer:

   It sends a result back to the place where the function was called. -> Option D

4. Quick Check:

   Return value = sends result back [OK]

Hint: Return values send results back to the caller [OK]

Common Mistakes:

• Confusing return values with variable declarations
• Thinking return values name the function
• Assuming return values are comments

2. Which of the following is the correct way to declare a function in Go that returns an integer?

easy

A. func add() int { return 5 }

B. func add() { return 5 }

C. func add int() { return 5 }

D. func add() int return 5

Solution

1. Step 1: Check function syntax for return type

   In Go, the return type is specified after parentheses: func name() type { ... }

2. Step 2: Verify each option

   func add() int { return 5 } correctly declares a function returning int. Others have syntax errors.

3. Final Answer:

   func add() int { return 5 } -> Option A

4. Quick Check:

   Return type after () = int [OK]

Hint: Return type goes after parentheses in function declaration [OK]

Common Mistakes:

• Placing return type before function name
• Omitting return type when returning a value
• Incorrect function syntax

3. What is the output of this Go code?

func multiply(a, b int) int {
    return a * b
}

func main() {
    result := multiply(3, 4)
    fmt.Println(result)
}

medium

A. 7

B. 34

C. Error: missing import

D. 12

Solution

1. Step 1: Check for required imports

   The code uses fmt.Println(result) but lacks import "fmt", causing a compile error: undefined fmt.

2. Step 2: Verify function logic

   The multiply function correctly computes 3*4=12, but the program won't compile or run without the import.

3. Final Answer:

   Error: missing import -> Option C

4. Quick Check:

   fmt.Println needs import "fmt" [OK]

Hint: fmt.Println requires import "fmt" [OK]

Common Mistakes:

• Forgetting import "fmt"
• Computing 3*4=12 but ignoring missing import
• Assuming code runs without imports

4. Identify the error in this Go function that returns two integers:

func divide(a, b int) (int, int) {
    return a / b
}

medium

A. Division operator is incorrect.

B. Function returns only one value but declares two return types.

C. Function parameters are missing types.

D. Function name is invalid.

Solution

1. Step 1: Check return type declaration

   The function declares two return values (int, int) but returns only one value.

2. Step 2: Identify mismatch in return statement

   Returning a single value causes a compile error because two values are expected.

3. Final Answer:

   Function returns only one value but declares two return types. -> Option B

4. Quick Check:

   Return count must match declared types [OK]

Hint: Return values count must match declared types [OK]

Common Mistakes:

• Returning fewer values than declared
• Wrong operator usage confusion
• Ignoring function signature

5. How can you write a Go function that returns both the sum and product of two integers?

hard

A. func calc(a, b int) (int, int) { return a+b, a*b }

B. func calc(a, b int) int { return a+b, a*b }

C. func calc(a, b int) (int) { return a+b, a*b }

D. func calc(a, b int) (int, int) { return a+b + a*b }

Solution

1. Step 1: Define function with two return types

   The function must declare two return types (int, int) for sum and product.

2. Step 2: Return sum and product as two values

   Return both values separated by a comma: return a+b, a*b.

3. Final Answer:

   func calc(a, b int) (int, int) { return a+b, a*b } -> Option A

4. Quick Check:

   Two return values with matching types [OK]

Hint: Return multiple values separated by commas [OK]

Common Mistakes:

• Returning multiple values with single return type
• Returning combined expression instead of two values
• Incorrect return type syntax