Omitting argument labels with _ in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the function without using the argument label.

Swift

func greet(_ name: String) {
    print("Hello, \(name)!")
}
greet([1])

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

Alabel: "Alice"

Bgreet: "Alice"

Cname: "Alice"

D"Alice"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the argument label when the function expects it to be omitted.

Trying to write the label explicitly even though it's omitted.

The underscore (_) in the function parameter means you omit the argument label when calling the function. So just pass the value directly.

2fill in blank

medium

Complete the function call by omitting the argument label as required.

Swift

func multiply(_ a: Int, by b: Int) -> Int {
    return a * b
}
let result = multiply([1], by: 5)

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

A3

Ba: 3

Cby: 3

Db: 3

Attempts:

3 left

💡 Hint

Common Mistakes

Adding the label 'a:' when the function expects it to be omitted.

Confusing the labels for the parameters.

The first parameter uses _ so you omit the label and just pass the value directly.

3fill in blank

hard

Fix the error by correctly calling the function that omits the first argument label.

Swift

func divide(_ numerator: Double, by denominator: Double) -> Double {
    return numerator / denominator
}
let quotient = divide([1], by: 2.0)

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

Anumerator: 10.0

B10.0

Cby: 10.0

Ddenominator: 10.0

Attempts:

3 left

💡 Hint

Common Mistakes

Including the label 'numerator:' causes a compile error.

Mixing up the labels for numerator and denominator.

The first parameter uses _ so you must omit the label and pass only the value.

4fill in blank

hard

Fill both blanks to define and call a function that omits the first argument label.

Swift

func power([1] base: Int, exponent: Int) -> Int {
    var result = 1
    for _ in 1...exponent {
        result *= base
    }
    return result
}
let value = power([2], exponent: 4)

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

A_

Bbase

Cexponent

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the underscore in the function definition.

Using the label when calling the function for the parameter with underscore.

Using _ before 'base' omits the argument label, so you call the function passing just the value for 'base'.

5fill in blank

hard

Fill all three blanks to define and call a function with two omitted argument labels.

Swift

func concatenate([1] first: String, [2] second: String, separator: String) -> String {
    return first + separator + second
}
let text = concatenate([3], "World", separator: ", ")

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

A_

Bfirst

Csecond

D"Hello"

Attempts:

3 left

💡 Hint

Common Mistakes

Including argument labels for parameters that use underscore.

Not using underscore in the function definition.

Using _ before 'first' and 'second' omits their argument labels, so you call the function passing values directly for those parameters.