Case conversion functions in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to convert the string to uppercase.

PHP

<?php
$text = "hello world";
echo [1]($text);
?>

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

Aucwords

Bstrtolower

Cstrtoupper

Ducfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Using strtolower which converts to lowercase.

Using ucfirst which only capitalizes the first letter.

The strtoupper function converts all characters in a string to uppercase.

2fill in blank

medium

Complete the code to convert the string to lowercase.

PHP

<?php
$text = "HELLO WORLD";
echo [1]($text);
?>

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

Astrtolower

Bucfirst

Cstrtoupper

Ducwords

Attempts:

3 left

💡 Hint

Common Mistakes

Using strtoupper which converts to uppercase.

Using ucfirst which only capitalizes the first letter.

The strtolower function converts all characters in a string to lowercase.

3fill in blank

hard

Fix the error in the code to capitalize the first letter of each word.

PHP

<?php
$text = "hello world";
echo [1]($text);
?>

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

Astrtoupper

Bucwords

Cstrtolower

Ducfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Using ucfirst which only capitalizes the first letter of the whole string.

Using strtoupper which makes all letters uppercase.

The ucwords function capitalizes the first letter of each word in a string.

4fill in blank

hard

Fill both blanks to convert the string to lowercase and then capitalize the first letter.

PHP

<?php
$text = "HELLO WORLD";
$lower = [1]($text);
$result = [2]($lower);
echo $result;
?>

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

Astrtolower

Bucwords

Cucfirst

Dstrtoupper

Attempts:

3 left

💡 Hint

Common Mistakes

Using strtoupper instead of strtolower first.

Using ucwords instead of ucfirst for the second step.

First, strtolower converts the string to all lowercase. Then, ucfirst capitalizes the first letter of the string.

5fill in blank

hard

Fill all three blanks to convert the string to lowercase, then capitalize the first letter of each word, and finally convert the whole string to uppercase.

PHP

<?php
$text = "hello world";
$lower = [1]($text);
$capitalized = [2]($lower);
$upper = [3]($capitalized);
echo $upper;
?>

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

Aucfirst

Bstrtolower

Cucwords

Dstrtoupper

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of functions.

Using ucfirst instead of ucwords for capitalizing each word.

First, strtolower makes all letters lowercase. Then, ucwords capitalizes the first letter of each word. Finally, strtoupper converts the entire string to uppercase.

Practice

1. Which PHP function converts all letters in a string to uppercase?
$text = "hello world";

easy

A. strtoupper()

B. strtolower()

C. ucfirst()

D. ucwords()

Solution

1. Step 1: Understand the function purpose

   strtoupper() converts all characters in a string to uppercase letters.

2. Step 2: Compare with other functions

   strtolower() makes all letters lowercase, ucfirst() capitalizes only the first letter, and ucwords() capitalizes the first letter of each word.

3. Final Answer:

   strtoupper() -> Option A

4. Quick Check:

   Uppercase function = strtoupper() [OK]

Hint: All uppercase letters? Use strtoupper() [OK]

Common Mistakes:

• Confusing strtoupper() with strtolower()
• Using ucfirst() to uppercase whole string
• Using ucwords() for full uppercase

2. Which of the following is the correct syntax to convert a string to lowercase in PHP?
$str = "HELLO";

easy

A. strtolower->$str();

B. strtolower $str;

C. strtolower($str);

D. strtolower{$str};

Solution

1. Step 1: Identify correct function call syntax

   In PHP, functions are called with parentheses enclosing arguments, like functionName(argument);.

2. Step 2: Check each option

   strtolower($str); uses correct syntax: strtolower($str);. Others have syntax errors or invalid usage.

3. Final Answer:

   strtolower($str); -> Option C

4. Quick Check:

   Function call syntax = strtolower($str); [OK]

Hint: Function calls need parentheses around arguments [OK]

Common Mistakes:

• Missing parentheses in function call
• Using arrow or braces incorrectly
• Confusing function call with variable access

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

$name = "john doe";
echo ucfirst($name);

medium

A. John doe

B. john Doe

C. JOHN DOE

D. john doe

Solution

1. Step 1: Understand ucfirst() behavior

   ucfirst() capitalizes only the first character of the entire string, leaving the rest unchanged.

2. Step 2: Apply to given string

   Input is "john doe". After ucfirst(), it becomes "John doe" (only first letter capitalized).

3. Final Answer:

   John doe -> Option A

4. Quick Check:

   ucfirst("john doe") = "John doe" [OK]

Hint: ucfirst() capitalizes only first letter of whole string [OK]

Common Mistakes:

• Expecting all words capitalized
• Confusing ucfirst() with ucwords()
• Assuming it converts whole string to uppercase

4. The following PHP code is intended to capitalize the first letter of each word in a string, but it does not work as expected:

$text = "hello world";
echo ucfirst($text);

What is the correct fix?

medium

A. Replace ucfirst() with strtoupper()

B. Replace ucfirst() with ucwords()

C. Replace ucfirst() with strtolower()

D. No fix needed, code is correct

Solution

1. Step 1: Identify function behavior

   ucfirst() capitalizes only the first letter of the entire string, not each word.

2. Step 2: Choose function to capitalize each word

   ucwords() capitalizes the first letter of every word in the string.

3. Final Answer:

   Replace ucfirst() with ucwords() -> Option B

4. Quick Check:

   Capitalize each word = ucwords() [OK]

Hint: Use ucwords() to capitalize first letter of each word [OK]

Common Mistakes:

• Using ucfirst() instead of ucwords()
• Using strtoupper() which uppercases all letters
• Thinking code is already correct

5. You have a string with mixed case: $input = "hElLo WoRLd";. You want to convert it so that only the first letter of each word is uppercase and the rest are lowercase. Which PHP code achieves this?

hard

A. $output = ucfirst(strtolower($input));

B. $output = strtoupper(ucwords($input));

C. $output = strtolower(ucfirst($input));

D. $output = ucwords(strtolower($input));

Solution

1. Step 1: Normalize string to lowercase

   Use strtolower() to convert all letters to lowercase first, so mixed case is fixed.

2. Step 2: Capitalize first letter of each word

   Apply ucwords() to capitalize the first letter of every word in the now lowercase string.

3. Final Answer:

   $output = ucwords(strtolower($input)); -> Option D

4. Quick Check:

   Lowercase then ucwords() = desired format [OK]

Hint: Lowercase first, then ucwords() for title case [OK]

Common Mistakes:

• Applying ucwords() before strtolower()
• Using strtoupper() which uppercases all letters
• Using ucfirst() which only capitalizes first letter of string