In-out parameters for mutation in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an in-out parameter in the function.

Swift

func increment(number: [1] Int) {
    number += 1
}

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

Alet

Bvar

Cinout

Dmutating

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'var' instead of 'inout' to declare a mutable parameter.

Forgetting to use 'inout' when intending to modify the parameter.

In Swift, inout is used to allow a function to modify a parameter's value.

2fill in blank

medium

Complete the code to call the function with an in-out parameter correctly.

Swift

var value = 5
increment([1]value)

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

A#

B*

C$

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the '&' symbol when passing the variable.

Using incorrect symbols like '*', '$', or '#'.

When passing an in-out parameter, you must prefix the variable with & to indicate it can be modified.

3fill in blank

hard

Fix the error in the function call by completing the blank.

Swift

func doubleValue(number: inout Int) {
    number *= 2
}

var num = 10
doubleValue(number: [1]num)

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

A&

B#

C$

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function without the '&' symbol.

Using other symbols like '*', '$', or '#'.

The & symbol is required before the variable name when passing it as an in-out parameter.

4fill in blank

hard

Fill both blanks to create a function that swaps two integers using in-out parameters.

Swift

func swapInts(a: [1] Int, b: [2] Int) {
    let temp = a
    a = b
    b = temp
}

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

Ainout

Bvar

Clet

Dmutating

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'var' or 'let' instead of 'inout'.

Declaring only one parameter as 'inout'.

Both parameters must be declared as inout to allow swapping their values.

5fill in blank

hard

Fill all three blanks to create a function that increments a number by a given amount using in-out parameters.

Swift

func incrementBy(amount: [1] Int, number: [2] Int) {
    number [3]= amount
}

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

Alet

Binout

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Declaring amount as inout instead of let.

Using '-=' instead of '+='.

Not using inout for number.

The amount is a constant input (let), number is an inout parameter to be modified, and += adds the amount to number.