Type coercion in operations in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code with mixed types?

Consider the following PHP code snippet. What will it output?

PHP

<?php
$a = '5';
$b = 3;
$c = $a + $b;
echo $c;
?>

A 8

B 53

C Error: Unsupported operand types

D 5

💡 Hint

PHP converts strings to numbers when using arithmetic operators.

In PHP, when adding a string containing a number to an integer, the string is converted to an integer. So '5' + 3 becomes 5 + 3 = 8.

❓ Predict Output

intermediate

What does this PHP code output when comparing string and integer?

What is the output of this PHP code snippet?

PHP

<?php
var_dump('10' == 10);
var_dump('10' === 10);
?>

A bool(true) bool(true)

B bool(false) bool(true)

C bool(false) bool(false)

D bool(true) bool(false)

💡 Hint

== compares values after type juggling, === compares both value and type.

The == operator converts '10' to integer 10 and compares values, so true. The === operator checks type and value, string vs integer, so false.

❓ Predict Output

advanced

What is the output of this PHP code with boolean and string addition?

Analyze the following PHP code and select the correct output.

PHP

<?php
$x = true + '2 apples';
echo $x;
?>

A 3

B 1

C 2 apples1

D Error: Unsupported operand types

💡 Hint

PHP converts booleans to integers and strings to numbers when used with + operator.

true converts to 1, '2 apples' converts to 2 (leading number), so 1 + 2 = 3.

❓ Predict Output

advanced

What error or output does this PHP code produce?

What happens when you run this PHP code?

PHP

<?php
$result = 'hello' - 5;
echo $result;
?>

A 0

B Error: Unsupported operand types

C -5

D 5

💡 Hint

PHP converts non-numeric strings to 0 when used in arithmetic.

'hello' converts to 0 because it does not start with a number, so 0 - 5 = -5.

❓ Predict Output

expert

What is the output of this PHP code with array and string addition?

Consider this PHP code. What will it output or error?

PHP

<?php
$a = [1, 2];
$b = '3';
$c = $a + $b;
echo gettype($c);
?>

A string

B Error: Unsupported operand types

C integer

D array

💡 Hint

PHP does not support adding arrays and strings with + operator.

Adding an array and a string with + operator causes a fatal error in PHP: Unsupported operand types.