PHP if Statement

An if statement is like a rule that says 'if it is raining, take an umbrella'. The code inside runs only when the condition is true, and otherwise PHP just skips it.

In this page:

Basic if Statement
Comparison inside Conditions
Logical AND (&&) in Conditions
Logical OR (||) in Conditions
Nested if Statements

Syntax

php

if (condition) {
    // runs only when condition is true
}

Basic if Statement

An if statement runs its block only when the condition inside the parentheses evaluates to true; if it's false, PHP skips the entire block and moves straight to whatever comes after it — no error, no output, just silently continuing execution.

Example: Basic if Statement

php

<?php
// Declare `$age`, set to `20`
$age = 20;
// Check whether `$age >= 18`
if ($age >= 18) {
    // Print "You are an adult." to the output
    echo "You are an adult.";
}
?>

Comparison inside Conditions

=== compares both value and type without any automatic conversion, which makes it the safer default inside an if condition — if ($status === active) won't accidentally match 1 or "1" the way the looser == operator sometimes can.

Example: Comparison inside Conditions

php

<?php
// Declare `$status`, set to "active"
$status = "active";
// Check whether `$status === 'active'`
if ($status === 'active') {
    // Print "Status is active." to the output
    echo "Status is active.";
}
?>

Logical AND (&&) in Conditions

&& inside a condition requires every joined expression to be true before the block runs — if ($age >= 18 && $hasConsent) only executes when both checks pass, which is exactly the pattern for enforcing multiple independent requirements at once.

Example: Logical AND (&&) in Conditions

php

<?php
// Declare `$age`, set to `20`
$age = 20;
// Declare `$hasConsent`, set to `true`
$hasConsent = true;
// Check whether `$age >= 18 && $hasConsent`
if ($age >= 18 && $hasConsent) {
    // Print "Access granted." to the output
    echo "Access granted.";
}
?>

Logical OR (||) in Conditions

|| inside a condition lets the block run if *any* one of the joined expressions is true, which suits situations with several acceptable paths to the same outcome — like accepting a login from either a username or an email address.

Example: Logical OR (||) in Conditions

php

<?php
// Declare `$username`, set to ""
$username = "";
// Declare `$email`, set to "[email protected]"
$email = "[email protected]";
// Check whether `$username || $email`
if ($username || $email) {
    // Print "Login accepted." to the output
    echo "Login accepted.";
}
?>

Nested if Statements

Placing one if inside another lets you check a second condition only once the first has already passed — useful when the second check genuinely only makes sense in that context (checking a file's contents, say, only after confirming the file exists at all).

Example: Nested if Statements

php

<?php
// Declare `$fileExists`, set to `true`
$fileExists = true;
// Check whether `$fileExists`
if ($fileExists) {
    // Declare `$content`, set to "sample data"
    $content = "sample data";
    // Check whether `!empty($content)`
    if (!empty($content)) {
        // Print "File exists and has content." to the output
        echo "File exists and has content.";
    }
}
?>

Chapter Quiz — Complete all 14 topics to unlock

0/14 topics done

Complete these topics first:

← Previous Lesson PHP Operator Precedence Next Lesson → PHP if-else Statement