Operators in PHP

What are Operators in PHP?

Operators are symbols that tell PHP to perform a specific action on one or more values.

For example:

$x = 10 + 5; // '+' is an operator

Here, + tells PHP to add two values.

Arithmetic Operators in PHP

Arithmetic operators are used to perform mathematical calculations.

Common Arithmetic Operators

Operator | Description        | Example
+        | Addition           | $a + $b
-        | Subtraction        | $a - $b
*        | Multiplication     | $a * $b
/        | Division           | $a / $b
%        | Modulus            | $a % $b

Example

$a = 10;
$b = 3;

echo $a + $b; // 13
echo $a - $b; // 7
echo $a * $b; // 30
echo $a / $b; // 3.33
echo $a % $b; // 1

Use case:

Used in calculations like totals, discounts, percentages, and counters.

Important:

Always ensure the divisor is not zero when performing division, as dividing by zero will cause a fatal error in PHP.

Modulus explained:

The modulus operator returns the remainder after division. It is commonly used to check if a number is even or odd, or to cycle through values (for example, alternating items in a loop).

Comparison Operators in PHP

Comparison operators are used to compare two values. They always return a boolean value (true or false).

Common Comparison Operators

Operator | Meaning                  | Example
-------- | ------------------------ | -----------
==       | Equal (value only)       | $a == $b
===      | Identical (value + type) | $a === $b
!=       | Not equal                | $a != $b
!==      | Not identical            | $a !== $b
>        | Greater than             | $a > $b
<        | Less than                | $a < $b
>=       | Greater or equal         | $a >= $b
<=       | Less or equal            | $a <= $b

Example

$a = 10;
$b = "10";

var_dump($a == $b);  // true
var_dump($a === $b); // false

Use case:

Validating user input, checking login credentials, or comparing values in conditions.

Logical Operators in PHP

Logical operators are used to combine multiple conditions.

Common Logical Operators

Operator | Meaning                 | Example
-------- | ----------------------- | ------------
&&       | AND (both must be true) | $a && $b
||       | OR (at least one true)  | $a || $b
!        | NOT (reverse condition) | !$a

Example

$age = 20;
$isLoggedIn = true;

if ($age > 18 && $isLoggedIn) {
    echo "Access granted";
}

Use case:

Used in decision-making like login systems, permissions, and validations.

Operator Precedence (Important Concept)

When multiple operators are used in one expression, PHP follows a priority order.

$result = 10 + 5 * 2; // Output: 20

Multiplication happens before addition.

To control order, use parentheses:

$result = (10 + 5) * 2; // Output: 30

Common Mistakes Beginners Make

1. Using = Instead of ==

if ($a = 10) { // Incorrect

Why it fails:

This assigns a value instead of comparing, which breaks logic.

2. Confusing == and ===

var_dump("5" == 5);  // true
var_dump("5" === 5); // false

Why it matters:

Loose comparison can produce unexpected results.

3. Ignoring Operator Precedence

$result = 10 + 5 * 2; // Not 30

Why it matters:

Assuming left-to-right evaluation leads to incorrect results.

4. Mixing && and || Without Parentheses

if ($age > 18 && $isLoggedIn || $isAdmin) {

Why it’s dangerous:

PHP evaluates && before ||, which may allow unintended access.

Correct version:

if (($age > 18 && $isLoggedIn) || $isAdmin) {

Real-World Example

$price = 100;
$discount = 20;
$isMember = true;

// Apply discount
$total = $price - $discount;

// Check access condition
if ($isMember && $total > 50) {
    echo "Final Price: ₹" . $total;
}

Output:

Final Price: ₹80

What this shows:

• Arithmetic (-)
• Comparison (>)
• Logical (&&)

Practice Exercise

Task 1

Add two numbers and print the result.

Expected Output:

15

Task 2

Compare two values using == and ===.

Expected Output:

true
false

Task 3

Write a condition using &&.

Expected Output:

Access granted

Summary

In this lesson, you learned how operators work in PHP. Arithmetic operators handle calculations, comparison operators evaluate values, and logical operators combine conditions to control decision-making in your applications.