Why operators matter in PHP - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add two numbers and print the result.

PHP

<?php
$a = 5;
$b = 3;
$result = $a [1] $b;
echo $result;
?>

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

A-

B*

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

The plus operator + adds two numbers together.

2fill in blank

medium

Complete the code to check if two values are equal.

PHP

<?php
$x = 10;
$y = 10;
if ($x [1] $y) {
    echo 'Equal';
} else {
    echo 'Not equal';
}
?>

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

A==

B!=

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using assignment = instead of comparison ==.

The double equals == operator checks if two values are equal.

3fill in blank

hard

Fix the error in the code to multiply two numbers correctly.

PHP

<?php
$num1 = 4;
$num2 = 7;
$product = $num1 [1] $num2;
echo $product;
?>

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

A-

B*

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or division instead of multiplication.

The asterisk * operator multiplies two numbers.

4fill in blank

hard

Fill both blanks to create an array of squares for numbers greater than 3.

PHP

<?php
$numbers = [1, 2, 3, 4, 5];
$squares = array_filter(array_map(fn($n) => $n[1]2, $numbers), fn($n) => $n [2] 9);
print_r($squares);
?>

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

A**

B>

C<

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of power, or wrong comparison operator.

The ** operator raises to a power. The filter keeps squares greater than 9.

5fill in blank

hard

Fill all three blanks to create an associative array with keys as uppercase letters and values greater than 2.

PHP

<?php
$items = ['a' => 1, 'b' => 3, 'c' => 5];
$result = array_filter(array_combine(array_map(fn($k) => [1]($k), array_keys($items)), $items), fn($v) => $v [2] 2 && $v [3] 6);
print_r($result);
?>

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

Astrtoupper

B>

C<

Dstrtolower

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase function or wrong comparison operators.

strtoupper converts keys to uppercase. Values are filtered to be greater than 2 and less than 6.

Practice

1. What does the == operator do in PHP?

easy

A. Checks if two values are identical in type and value

B. Assigns a value to a variable

C. Adds two numbers together

D. Checks if two values are equal in value

Solution

1. Step 1: Understand the == operator

   The == operator compares two values to see if they are equal, ignoring type differences.

2. Step 2: Differentiate from other operators

   The = operator assigns values, + adds numbers, and === checks both value and type.

3. Final Answer:

   Checks if two values are equal in value -> Option D

4. Quick Check:

   == means equal value [OK]

Hint: Remember: == compares values, not types [OK]

Common Mistakes:

• Confusing == with = (assignment)
• Thinking == checks type too
• Mixing == with ===

2. Which of the following is the correct way to increment a variable $count by 1 in PHP?

easy

A. $count += 1;

B. $count = 1+;

C. $count =+ 1;

D. $count ++=;

Solution

1. Step 1: Identify the correct increment syntax

   The operator += adds a value to the variable and assigns the result back.

2. Step 2: Check each option's syntax

   $count =+ 1; uses =+ which is invalid. $count = 1+; has misplaced plus sign. $count ++=; is invalid syntax. Only $count += 1; is correct.

3. Final Answer:

   $count += 1; -> Option A

4. Quick Check:

   Use += to add and assign [OK]

Hint: Use += to add and assign in one step [OK]

Common Mistakes:

• Writing =+ instead of += causes errors
• Misplacing the plus sign
• Using invalid syntax like ++=

3. What will be the output of this PHP code?

$a = 5;
$b = 10;
$result = $a > $b ? 'Yes' : 'No';
echo $result;

medium

A. 5

B. Yes

C. No

D. 10

Solution

1. Step 1: Evaluate the comparison $a > $b

   Since 5 is not greater than 10, the condition is false.

2. Step 2: Apply the ternary operator

   Because the condition is false, the expression returns 'No'.

3. Final Answer:

   No -> Option C

4. Quick Check:

   5 > 10 is false, so output is 'No' [OK]

Hint: Ternary returns first if true, else second [OK]

Common Mistakes:

• Assuming 5 > 10 is true
• Confusing ternary syntax
• Expecting numeric output instead of string

4. Find the error in this PHP code snippet:

$x = 10;
if ($x = 5) {
  echo 'Equal';
} else {
  echo 'Not Equal';
}

medium

A. The variable $x is not declared before use

B. The assignment operator '=' is used instead of comparison '==' in the if condition

C. The echo statements are missing semicolons

D. The else block is not allowed after if

Solution

1. Step 1: Check the if condition operator

   The code uses = which assigns 5 to $x instead of comparing.

2. Step 2: Understand the effect of assignment in condition

   Assignment returns the assigned value (5), which is truthy, so 'Equal' always prints regardless of original $x.

3. Final Answer:

   The assignment operator '=' is used instead of comparison '==' in the if condition -> Option B

4. Quick Check:

   Use == to compare, not = [OK]

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

Common Mistakes:

• Using = instead of == in conditions
• Thinking assignment returns boolean
• Ignoring that assignment inside if is valid but wrong logic

5. You want to check if a variable $value is either 0 or an empty string '' in PHP. Which operator should you use to correctly test this condition?

hard

A. Use $value === 0 || $value === ''

B. Use $value == 0 || $value == ''

C. Use $value = 0 || $value = ''

D. Use $value != 0 && $value != ''

Solution

1. Step 1: Understand the difference between == and ===

   == compares values loosely, === compares value and type strictly.

2. Step 2: Choose strict comparison for exact match

   To check if $value is exactly 0 (integer) or exactly empty string, use === to avoid false matches.

3. Step 3: Avoid assignment in condition

   Use $value = 0 || $value = '' uses = which assigns values, causing errors.

4. Final Answer:

   Use $value === 0 || $value === '' -> Option A

5. Quick Check:

   Use === for exact type and value checks [OK]

Hint: Use === to check both type and value exactly [OK]

Common Mistakes:

• Using = instead of == or ===
• Using == which allows type juggling
• Using && instead of || for this check