Spaceship operator in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code using the spaceship operator?

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

PHP

<?php
$a = 5;
$b = 10;
echo $a <=> $b;
?>

A -1

B 1

C 0

D Error

💡 Hint

The spaceship operator returns -1 if the left is less than the right.

The spaceship operator (<=>) returns -1 when the left value is less than the right value. Here, 5 is less than 10, so it returns -1.

❓ Predict Output

intermediate

What does this PHP code output when comparing equal values?

Look at this PHP code using the spaceship operator. What will it print?

PHP

<?php
$x = 7;
$y = 7;
echo $x <=> $y;
?>

A null

B -1

C 1

D 0

💡 Hint

The spaceship operator returns 0 when both sides are equal.

When both values are equal, the spaceship operator returns 0. Here, both $x and $y are 7.

❓ Predict Output

advanced

What is the output of this PHP code comparing a string and an integer?

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

PHP

<?php
$a = 'apple';
$b = 5;
echo $a <=> $b;
?>

A 0

B -1

C 1

D Error

💡 Hint

When comparing a string to an integer, the string is converted to a number. 'apple' converts to 0.

When one operand is a number and the other is a string, the string is converted to a number. 'apple' converts to 0, and 0 < 5, so the spaceship operator returns -1.

❓ Predict Output

advanced

What is the output of this PHP code comparing arrays with the spaceship operator?

Analyze this PHP code and determine its output.

PHP

<?php
$arr1 = [1, 2, 3];
$arr2 = [1, 2, 4];
echo $arr1 <=> $arr2;
?>

A Error

B 0

C -1

D 1

💡 Hint

The spaceship operator compares arrays element by element.

The spaceship operator compares arrays element-wise. Since 3 is less than 4 at the third element, it returns -1.

🧠 Conceptual

expert

What is the value of $result after this PHP code runs?

Given this PHP code, what is the value stored in $result?

PHP

<?php
function compareValues(mixed $a, mixed $b): int {
    return $a <=> $b;
}

$result = compareValues(3.5, 3);
?>

A 1

B -1

C 0

D TypeError

💡 Hint

The spaceship operator works with floats and integers.

3.5 is greater than 3, so the spaceship operator returns 1.