PHP Boolean: A Tutorial with Examples

A Boolean in PHP represents true or false values.

It is commonly used in conditions, loops, and logical operations.

This tutorial will cover:

1. What Are Boolean Values in PHP?

A Boolean is a data type that can have only two values:

• true
• false

Example:

<?php
$bool1 = true;
$bool2 = false;

var_dump($bool1); // Output: bool(true)
var_dump($bool2); // Output: bool(false)
?>

• The var_dump() function is used to check the data type.

2. Declaring and Using Boolean Variables

Example:

<?php
$is_active = true;
$is_logged_in = false;

if ($is_active) {
    echo "The user is active!";
} else {
    echo "The user is not active.";
}
?>

• if ($is_active) is true, so it prints “The user is active!”.

3. Boolean Comparison Operators

Comparison operators return Boolean values (true or false).

Comparison Operators in PHP

Example:

<?php
$x = 10;
$y = 20;

var_dump($x > $y);  // Output: bool(false)
var_dump($x < $y);  // Output: bool(true)
var_dump($x == 10); // Output: bool(true)
?>

4. Boolean Logical Operators

Logical operators are used to combine Boolean expressions.

Logical Operators in PHP

Example:

<?php
$is_admin = true;
$is_logged_in = false;

// AND Operator
if ($is_admin && $is_logged_in) {
    echo "Admin panel access granted!";
} else {
    echo "Access denied!";
}

// OR Operator
if ($is_admin || $is_logged_in) {
    echo "Limited access granted!";
}
?>

• The && (AND) condition fails because one value is false.
• The || (OR) condition passes because one value is true.

5. Boolean Type Casting and Conversion

PHP automatically converts other data types to Boolean when used in a Boolean context.

Truthy and Falsy Values in PHP

Example:

<?php
var_dump((bool) 0);        // Output: bool(false)
var_dump((bool) 42);       // Output: bool(true)
var_dump((bool) "hello");  // Output: bool(true)
var_dump((bool) "");       // Output: bool(false)
var_dump((bool) []);       // Output: bool(false)
?>

• (bool) $variable converts the value to a Boolean.

6. Boolean in Conditional Statements

Booleans are commonly used in if-else conditions.

Example:

<?php
$is_logged_in = true;

if ($is_logged_in) {
    echo "Welcome, user!";
} else {
    echo "Please log in.";
}
?>

• if ($is_logged_in) is true, so “Welcome, user!” is printed.

7. Boolean in Loops

Booleans can control loops.

Example: Using Boolean in a While Loop

<?php
$counter = 0;
$keep_running = true;

while ($keep_running) {
    echo "Iteration: $counter <br>";
    $counter++;

    if ($counter >= 5) {
        $keep_running = false; // Stop the loop
    }
}
?>

• The loop runs until $keep_running is false.

8. Boolean Functions in PHP

Some PHP functions return Boolean values.

Example Functions:

Example:

<?php
$value = true;
var_dump(is_bool($value)); // Output: bool(true)

$name = "";
var_dump(empty($name)); // Output: bool(true)

$option = "yes";
var_dump(filter_var($option, FILTER_VALIDATE_BOOLEAN)); // Output: bool(true)
?>

Conclusion

• Booleans (true/false) are fundamental in PHP for logical operations and flow control.
• Comparison and logical operators help in decision-making.
• PHP automatically converts values to Boolean in conditions.
• Boolean functions assist in checking and validating data.