Integer type and behavior in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an integer variable with value 10.

PHP

<?php
$number = [1];
echo $number;
?>

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

A10

B"10"

C10.0

D'10'

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the number makes it a string, not an integer.

Using a decimal point makes it a float, not an integer.

The value 10 without quotes is an integer in PHP.

2fill in blank

medium

Complete the code to check if a variable is an integer using a built-in function.

PHP

<?php
$var = 5;
if ([1]($var)) {
    echo "Integer";
} else {
    echo "Not integer";
}
?>

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

Ais_int

Bis_string

Cis_float

Dis_numeric

Attempts:

3 left

💡 Hint

Common Mistakes

Using is_string or is_float instead of is_int.

Using is_numeric which returns true for floats and numeric strings too.

The function is_int() checks if a variable is an integer.

3fill in blank

hard

Fix the error in the code to correctly add two integers and print the result.

PHP

<?php
$a = 7;
$b = 3;
$sum = $a [1] $b;
echo $sum;
?>

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

A-

B+

C.

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using the dot operator . which concatenates strings instead of adding numbers.

Using subtraction or multiplication operators instead of addition.

The plus sign + adds two numbers in PHP. The dot . is for string concatenation.

4fill in blank

hard

Fill both blanks to create an array of squares for numbers 1 to 5 using a loop.

PHP

<?php
$squares = [];
for ($i = 1; $i [1] 5; $i++) {
    $squares[] = $i [2] $i;
}
print_r($squares);
?>

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

A<=

B*

C+

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of <= causes the loop to stop before 5.

Using addition instead of multiplication for squares.

The loop runs while $i is less than or equal to 5. The square is calculated by multiplying $i by itself.

5fill in blank

hard

Fill all three blanks to create an associative array with keys as numbers and values as their cubes, only for numbers greater than 2.

PHP

<?php
$cubes = [];
foreach (range(1, 5) as [1]) {
    if ([2] > 2) {
        $cubes[[3]] = [2] * [2] * [2];
    }
}
print_r($cubes);
?>

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

A$num

D$val

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in the loop and condition causes errors.

Using undefined variables like $val.

The variable $num is used for the loop and conditions consistently to represent each number.

Practice

1. Which of the following is a valid integer value in PHP?

easy

A. 42

B. 3.14

C. "100"

D. true

Solution

1. Step 1: Understand integer definition in PHP

   Integers are whole numbers without decimals, like 42 or -7.

2. Step 2: Check each option

   42 is 42, a whole number. 3.14 is 3.14, a float. "100" is a string. true is a boolean.

3. Final Answer:

   42 -> Option A

4. Quick Check:

   Integer = 42 [OK]

Hint: Integers have no decimal point or quotes [OK]

Common Mistakes:

• Confusing strings with integers
• Thinking floats are integers
• Using booleans as integers

2. Which of the following is the correct way to declare an integer variable in PHP?

easy

A. $num = 10;

B. $num = '10';

C. $num = 10.0;

D. $num = true;

Solution

1. Step 1: Identify integer assignment syntax

   In PHP, integers are assigned without quotes and without decimal points.

2. Step 2: Evaluate each option

   $num = '10'; assigns a string '10'. $num = 10; assigns integer 10 correctly. $num = 10.0; assigns a float 10.0. $num = true; assigns a boolean true.

3. Final Answer:

   $num = 10; -> Option A

4. Quick Check:

   Integer assignment = $num = 10; [OK]

Hint: No quotes or decimals for integers [OK]

Common Mistakes:

• Using quotes around numbers
• Assigning floats instead of integers
• Confusing booleans with integers

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

$a = 5;
$b = 2;
$c = $a / $b;
echo (int)$c;

medium

A. 2.5

B. 3

C. Error

D. 2

Solution

1. Step 1: Calculate division result

   $a / $b = 5 / 2 = 2.5 (float)

2. Step 2: Cast float to integer

   (int)2.5 converts to 2 by dropping decimal part.

3. Final Answer:

   2 -> Option D

4. Quick Check:

   Integer cast truncates decimals = 2 [OK]

Hint: Casting float to int drops decimals [OK]

Common Mistakes:

• Expecting rounding instead of truncation
• Confusing output with float value
• Thinking casting causes error

4. Identify the error in this PHP code snippet:

$num = 0123;
echo $num;

medium

A. Outputs 123 as decimal

B. Outputs 83 because of octal interpretation

C. Syntax error due to leading zero

D. Runtime error

Solution

1. Step 1: Understand leading zero in integer literals

   In PHP, numbers starting with 0 are octal (base 8) numbers.

2. Step 2: Convert octal 0123 to decimal

   Octal 123 = 1*64 + 2*8 + 3 = 64 + 16 + 3 = 83 decimal.

3. Final Answer:

   Outputs 83 because of octal interpretation -> Option B

4. Quick Check:

   Leading zero means octal = 83 [OK]

Hint: Leading zero means octal number in PHP [OK]

Common Mistakes:

• Assuming leading zero is ignored
• Expecting decimal output 123
• Thinking it causes syntax error

5. You want to store a large integer value beyond PHP's 32-bit limit. Which approach correctly handles this in PHP?

hard

A. Use a float type to store the large number

B. Use an array to split the number into parts

C. Use a string to store the number and perform math with BCMath functions

D. Use an integer variable; PHP automatically supports large integers

Solution

1. Step 1: Recognize PHP integer size limits

   PHP integers have size limits (32-bit or 64-bit depending on system). Large numbers can overflow.

2. Step 2: Choose correct method for large integers

   Using strings with BCMath functions allows precise math on large numbers beyond integer limits.

3. Final Answer:

   Use a string to store the number and perform math with BCMath functions -> Option C

4. Quick Check:

   Large integer math needs strings + BCMath [OK]

Hint: Use strings + BCMath for big integers [OK]

Common Mistakes:

• Using floats causes precision loss
• Assuming PHP integers auto-expand
• Trying to split number manually in arrays