PHP if Statement: Run Code Only When a Condition Is True

Programs need to make decisions. The if statement runs a block of code only when a condition is true.

index.php

PHP

<?php
$age = 20;

if ($age >= 18) {
    echo "You can vote.";
}

Output

OUTPUT

You can vote.

The condition goes inside the brackets. If it is true, the code inside the curly braces runs. If it is false, PHP skips it.

index.php

PHP

<?php
$age = 15;

if ($age >= 18) {
    echo "You can vote.";
}

echo "Done.";

Output

OUTPUT

Done.

What a condition is

A condition is any expression that PHP can treat as true or false. Comparisons are the most common kind.

index.php

PHP

<?php
$stock = 0;

if ($stock === 0) {
    echo "Sold out";
}

Output

OUTPUT

Sold out

If a variable already holds true or false, you do not need a comparison.

index.php

PHP

<?php
$isLoggedIn = true;

if ($isLoggedIn) {
    echo "Welcome back!";
}

Output

OUTPUT

Welcome back!

Use ! to run code when something is not true.

index.php

PHP

<?php
$isLoggedIn = false;

if (!$isLoggedIn) {
    echo "Please log in.";
}

Output

OUTPUT

Please log in.

index.php

PHP

<?php
$total = 1200;

if ($total > 1000) {
    $discount = $total * 0.1;
    echo "Discount: $discount\n";
    echo "Free shipping applied.";
}

Output

OUTPUT

1
2

Discount: 120
Free shipping applied.

index.php

PHP

<?php
$age = 25;
$hasId = true;

if ($age >= 18 && $hasId) {
    echo "Entry allowed";
}

Output

OUTPUT

Entry allowed

warning

if ($score = 10) assigns 10 to $score and is always true. You want == or, better, ===. See Comparison Operators.

Write an if that prints Too short when $password has fewer than 8 characters.

Show a possible solution

index.php

PHP

<?php
$password = "abc123";

if (strlen($password) < 8) {
    echo "Too short";
}

Output

OUTPUT

Too short