Comparison operators (loose and strict) in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of loose equality with different types

What is the output of this PHP code?

$a = 0;
$b = '0';
var_dump($a == $b);

PHP

$a = 0;
$b = '0';
var_dump($a == $b);

A string(1) "0"

B bool(false)

C int(0)

D bool(true)

💡 Hint

Loose equality compares values after type juggling.

The loose equality operator (==) converts types if needed. Here, integer 0 and string '0' are considered equal, so var_dump outputs bool(true).

❓ Predict Output

intermediate

Output of strict equality with different types

What is the output of this PHP code?

$a = 0;
$b = '0';
var_dump($a === $b);

PHP

$a = 0;
$b = '0';
var_dump($a === $b);

A bool(true)

B bool(false)

C int(0)

D string(1) "0"

💡 Hint

Strict equality checks both value and type.

The strict equality operator (===) requires both value and type to be the same. Here, integer 0 and string '0' differ in type, so var_dump outputs bool(false).

❓ Predict Output

advanced

Result of comparing null and empty string with loose equality

What is the output of this PHP code?

$a = null;
$b = '';
var_dump($a == $b);

PHP

$a = null;
$b = '';
var_dump($a == $b);

A bool(false)

B NULL

C bool(true)

D string(0) ""

💡 Hint

Loose equality considers null equal to empty string.

In PHP, null and empty string are NOT equal with loose equality (==). So var_dump outputs bool(false).

❓ Predict Output

advanced

Output of comparing boolean false and string '0' with loose equality

What is the output of this PHP code?

$a = false;
$b = '0';
var_dump($a == $b);

PHP

$a = false;
$b = '0';
var_dump($a == $b);

A bool(false)

B int(0)

C bool(true)

D string(1) "0"

💡 Hint

Loose equality converts both to boolean for comparison.

When comparing false and '0' with loose equality, PHP converts '0' to false, so they are equal and var_dump outputs bool(true).

❓ Predict Output

expert

Output of comparing array and string with loose equality

What is the output of this PHP code?

$a = [];
$b = '';
var_dump($a == $b);

PHP

$a = [];
$b = '';
var_dump($a == $b);

A bool(false)

B bool(true)

C array(0) {}

D string(0) ""

💡 Hint

Empty arrays and empty strings are equal with loose equality.

In PHP, an empty array and an empty string are NOT equal with loose equality (==). So var_dump outputs bool(false).