PHP Conditional Statements

Conditional statements execute different code blocks based on conditions, enabling dynamic decision-making in your applications.

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The if Statement

Executes code only when a condition is true.

$age = 18;

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

// Multiple conditions
if ($score >= 80 && $attendance >= 85) {
    echo "Excellent performance!";
}

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The if-else Statement

Provides an alternative when the condition is false.

$temperature = 15;

if ($temperature > 25) {
    echo "It's hot outside.";
} else {
    echo "It's cool outside.";
}

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The elseif Statement

Checks multiple conditions in sequence.

$score = 75;

if ($score >= 90) {
    echo "Grade: A";
} elseif ($score >= 80) {
    echo "Grade: B";
} elseif ($score >= 70) {
    echo "Grade: C";
} else {
    echo "Grade: F";
}

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The switch Statement

Cleaner alternative to multiple elseif when checking one variable against multiple values.

$orderStatus = "shipped";

switch ($orderStatus) {
    case "pending":
        echo "Order is being processed.";
        break;
    case "shipped":
        echo "Order is on the way!";
        break;
    case "delivered":
        echo "Order has been delivered.";
        break;
    default:
        echo "Unknown status.";
}

Important: Always use break to prevent fall-through.

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Ternary Operator

Shorthand for simple if-else assignments.

$age = 20;
$status = ($age >= 18) ? "Adult" : "Minor";

// Equivalent to:
if ($age >= 18) {
    $status = "Adult";
} else {
    $status = "Minor";
}

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Null Coalescing Operator (??)

Returns the first non-null value; useful for handling undefined variables.

// Replaces isset() ternary
$username = $_GET['username'] ?? 'Guest';

// Chain multiple fallbacks
$config = $userConfig ?? $defaultConfig ?? 'fallback';

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Things to Notes

1. Use strict comparison (===) to avoid type coercion bugs.

2. Extract complex conditions into variables for readability.

// Harder to read
if ($user['age'] >= 18 && $user['verified'] && $user['status'] !== 'banned') { }

// Better
$canAccess = $user['age'] >= 18 && $user['verified'] && $user['status'] !== 'banned';
if ($canAccess) { }

3. Use switch for multiple value checks instead of many elseif statements.

4. Avoid deep nesting: use early returns or logical operators.

5. Use ternary only for simple assignments: don’t nest ternary operators.