Comparison operators in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a is equal to b.

Swift

let isEqual = a [1] b

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

A==

B=

C!=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '==' for comparison.

Using '!=' which checks for inequality.

The operator == checks if two values are equal in Swift.

2fill in blank

medium

Complete the code to check if x is greater than y.

Swift

if x [1] y {
    print("x is greater")
}

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

A>

B<=

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' which means less than.

Using '==' which checks equality.

The operator > checks if the left value is greater than the right value.

3fill in blank

hard

Fix the error in the code to check if number is not equal to 10.

Swift

if number [1] 10 {
    print("Number is not 10")
}

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

A=

B!=

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' which causes a syntax error in condition.

Using '==' which checks for equality, not inequality.

The operator != checks if two values are not equal.

4fill in blank

hard

Fill both blanks to create a dictionary of words and their lengths, including only words longer than 3 characters.

Swift

let lengths = [String: Int](uniqueKeysWithValues: words.map { word in (word, word[1]) }).filter { $0.value [2] 3 }

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

A.count

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the filter condition.

Using '==' which only selects words of length exactly 3.

.count gets the length of the word, and > filters words longer than 3 characters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase keys and values greater than 0.

Swift

let result = Dictionary(uniqueKeysWithValues: data.map { ([1], [2]) in ([3], [2]) }).filter { $0.value > 0 }

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

Akey

Bvalue

Ckey.uppercased()

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'item' instead of 'key' or 'value'.

Not converting the key to uppercase.

key and value are tuple names, and key.uppercased() converts the key to uppercase.

Practice

1. Which of the following comparison operators checks if two values are equal in Swift?

easy

A. ==

B. !=

C. >

D. <=

Solution

1. Step 1: Understand the equality operator

   The operator == is used to check if two values are equal in Swift.

2. Step 2: Compare with other operators

   != means not equal, > means greater than, and <= means less than or equal to.

3. Final Answer:

   == -> Option A

4. Quick Check:

   Equality operator = == [OK]

Hint: Remember: double equals means equality check [OK]

Common Mistakes:

• Confusing == with = (assignment)
• Using != to check equality
• Mixing > and < with equality

2. Which of the following is the correct syntax to check if variable a is not equal to variable b in Swift?

easy

A. a != b

B. a =! b

C. a !== b

D. a <> b

Solution

1. Step 1: Identify the not equal operator in Swift

   Swift uses != to check if two values are not equal.

2. Step 2: Check syntax correctness

   a != b is correct. a =! b is invalid syntax, !== is for identity comparison in some languages but not for value inequality in Swift, and <> is not a Swift operator.

3. Final Answer:

   a != b -> Option A

4. Quick Check:

   Not equal operator = != [OK]

Hint: Not equal always has ! before = [OK]

Common Mistakes:

• Swapping = and ! in != operator
• Using === instead of !=
• Using <> which is not valid in Swift

3. What will be the output of the following Swift code?

let x = 10
let y = 20
print(x > y)

medium

A. true

B. 10

C. 20

D. false

Solution

1. Step 1: Understand the comparison

   The code compares if x (10) is greater than y (20).

2. Step 2: Evaluate the comparison

   Since 10 is not greater than 20, the expression x > y is false.

3. Final Answer:

   false -> Option D

4. Quick Check:

   10 > 20 = false [OK]

Hint: Compare values carefully, > means strictly greater [OK]

Common Mistakes:

• Assuming 10 > 20 is true
• Confusing > with <
• Printing variable values instead of boolean

4. Identify the error in the following Swift code snippet:

let a = 5
let b = 10
if a = b {
    print("Equal")
} else {
    print("Not Equal")
}

medium

A. Using print instead of println

B. Missing parentheses around condition

C. Using = instead of == in if condition

D. Variables a and b must be var, not let

Solution

1. Step 1: Check the if condition syntax

   The condition uses a = b, which is assignment, not comparison.

2. Step 2: Correct operator for comparison

   To compare values, Swift requires == instead of =.

3. Final Answer:

   Using = instead of == in if condition -> Option C

4. Quick Check:

   Comparison needs ==, not = [OK]

Hint: Use == for comparison, = is assignment [OK]

Common Mistakes:

• Using = instead of == in conditions
• Thinking parentheses are mandatory in Swift if
• Confusing print and println functions

5. You want to check if a number n is between 10 and 20 inclusive in Swift. Which of the following expressions correctly uses comparison operators to do this?

hard

A. n > 10 || n < 20

B. n >= 10 && n <= 20

C. n == 10 && n == 20

D. n != 10 && n != 20

Solution

1. Step 1: Understand the range condition

   To check if n is between 10 and 20 inclusive, it must be greater than or equal to 10 and less than or equal to 20.

2. Step 2: Analyze each option

   n >= 10 && n <= 20 uses n >= 10 && n <= 20, which correctly checks the inclusive range. n > 10 || n < 20 uses OR which is incorrect for range. n == 10 && n == 20 checks if n equals both 10 and 20 simultaneously, which is impossible. n != 10 && n != 20 checks if n is not 10 and not 20, which does not ensure the range.

3. Final Answer:

   n >= 10 && n <= 20 -> Option B

4. Quick Check:

   Inclusive range uses >= and <= with AND [OK]

Hint: Use && with >= and <= for inclusive range checks [OK]

Common Mistakes:

• Using || instead of && for range
• Checking equality to both ends at once
• Using != which excludes values instead of range