Char type and Unicode behavior in Kotlin - Mini Project: Build & Apply

Char type and Unicode behavior

📖 Scenario: You are working with characters in Kotlin and want to understand how the Char type works with Unicode values.

🎯 Goal: Learn how to create Char variables, use Unicode escape sequences, and print characters and their Unicode codes.

📋 What You'll Learn

Create Char variables with normal characters and Unicode escape sequences

Create an Int variable to hold the Unicode code of a character

Use println to display characters and their Unicode codes

💡 Why This Matters

🌍 Real World

Understanding <code>Char</code> and Unicode is important when working with text, symbols, and emojis in apps.

💼 Career

Many programming jobs require handling text data correctly, including Unicode characters for internationalization.

1

Create Char variables

Create a Char variable called letterA with the value 'A' and another Char variable called unicodeHeart with the Unicode escape sequence '\u2764'.

Kotlin

# Your code here

Hint

Use single quotes for Char values. Unicode escape sequences start with \u followed by four hex digits.

2

Get Unicode code of a Char

Create an Int variable called codeOfHeart and assign it the Unicode code of the unicodeHeart character using unicodeHeart.code.

Kotlin

val letterA: Char = 'A'
val unicodeHeart: Char = '\u2764'
# Your code here

Hint

Use the code property of a Char to get its Unicode integer value.

3

Print characters and Unicode codes

Use println to print letterA, unicodeHeart, and codeOfHeart each on its own line.

Kotlin

val letterA: Char = 'A'
val unicodeHeart: Char = '\u2764'
val codeOfHeart: Int = unicodeHeart.code
# Your code here

Hint

Use println three times, once for each variable.

4

Final output check

Run the program and observe the output showing the character A, the heart symbol, and the Unicode code 10084.

Kotlin

val letterA: Char = 'A'
val unicodeHeart: Char = '\u2764'
val codeOfHeart: Int = unicodeHeart.code
println(letterA)
println(unicodeHeart)
println(codeOfHeart)
# Your code here

Hint

The output should show the letter A, the heart symbol, and the number 10084 each on its own line.

Practice

1. Which of the following correctly declares a Char variable in Kotlin?

easy

A. val letter: Char = `A`

B. val letter: Char = "A"

C. val letter: Char = A

D. val letter: Char = 'A'

Solution

1. Step 1: Understand Char declaration syntax

   In Kotlin, a Char value must be enclosed in single quotes, like 'A'.

2. Step 2: Check each option

   val letter: Char = 'A' uses single quotes correctly. val letter: Char = "A" uses double quotes (String). val letter: Char = A has no quotes (invalid). val letter: Char = `A` uses backticks (invalid for Char).

3. Final Answer:

   val letter: Char = 'A' -> Option D

4. Quick Check:

   Char uses single quotes = A [OK]

Hint: Char values use single quotes, not double quotes [OK]

Common Mistakes:

• Using double quotes instead of single quotes
• Omitting quotes around the character
• Using backticks instead of quotes

2. Which of the following is the correct way to get the Unicode code of a Char in Kotlin?

easy

A. val code = 'A'.code

B. val code = 'A'.unicodeValue()

C. val code = 'A'.toInt()

D. val code = 'A'.unicode

Solution

1. Step 1: Recall Kotlin Char Unicode property

   Kotlin provides the code property to get the Unicode integer value of a Char.

2. Step 2: Evaluate options

   val code = 'A'.code uses code property correctly. val code = 'A'.toInt() uses toInt() which does not exist for Char. Options B and D use non-existent methods/properties.

3. Final Answer:

   val code = 'A'.code -> Option A

4. Quick Check:

   Use .code to get Unicode number [OK]

Hint: Use .code property to get Unicode number from Char [OK]

Common Mistakes:

• Using non-existent toInt() method on Char
• Trying non-existent methods like unicodeValue()
• Accessing properties that don't exist

3. What is the output of the following Kotlin code?

val ch: Char = 'Z'
println(ch.code)

medium

A. 122

B. 90

C. Z

D. SyntaxError

Solution

1. Step 1: Identify the Char and property used

   The variable ch is assigned the character 'Z'. The code prints ch.code, which returns the Unicode integer value.

2. Step 2: Find Unicode value of 'Z'

   The Unicode code for uppercase 'Z' is 90.

3. Final Answer:

   90 -> Option B

4. Quick Check:

   'Z'.code = 90 [OK]

Hint: Remember uppercase 'Z' Unicode is 90 [OK]

Common Mistakes:

• Confusing uppercase and lowercase Unicode values
• Expecting the character itself instead of code
• Thinking code property causes syntax error

4. Identify the error in this Kotlin code snippet:

val ch: Char = "A"
println(ch.code)

medium

A. code property does not exist for Char

B. Missing semicolon after println

C. Using double quotes for Char assignment

D. Variable ch should be Int, not Char

Solution

1. Step 1: Check Char assignment syntax

   Chars must be assigned using single quotes, not double quotes. Double quotes create a String.

2. Step 2: Verify other parts

   Semicolons are optional in Kotlin, so no error there. The code property exists for Char. Variable type Char is correct.

3. Final Answer:

   Using double quotes for Char assignment -> Option C

4. Quick Check:

   Char needs single quotes, not double [OK]

Hint: Chars use single quotes; double quotes mean String [OK]

Common Mistakes:

• Thinking semicolons are mandatory
• Believing code property is invalid
• Confusing Char and Int types

5. Given a list of characters val chars = listOf('a', 'B', 'c', 'D'), which Kotlin expression correctly filters only uppercase letters using Unicode properties?

hard

A. chars.filter { it.isUpperCase() }

B. chars.filter { it.code > 90 }

C. chars.filter { it.code.isUpperCase() }

D. chars.filter { it > 'Z' }

Solution

1. Step 1: Understand filtering uppercase letters

   Kotlin's Char class has a method isUpperCase() that returns true if the character is uppercase.

2. Step 2: Evaluate each option

   chars.filter { it.isUpperCase() } uses isUpperCase() correctly. chars.filter { it.code > 90 } filters by code > 90, which excludes all uppercase letters (A-Z: 65-90). chars.filter { it.code.isUpperCase() } calls isUpperCase() on an Int (code), which does not exist. chars.filter { it > 'Z' } compares chars incorrectly.

3. Final Answer:

   chars.filter { it.isUpperCase() } -> Option A

4. Quick Check:

   Use isUpperCase() to filter uppercase chars [OK]

Hint: Use isUpperCase() method to filter uppercase chars [OK]

Common Mistakes:

• Filtering by numeric code incorrectly
• Calling isUpperCase() on the Unicode code (Int)
• Using wrong comparison operators for chars