Lesson 4 • Beginner

Control Flow 🔀

Control program logic with if/elseif/else, ternary operators, switch statements, and PHP 8's match expression.

What You'll Learn in This Lesson

• If / elseif / else for branching logic
• Nested conditions and combining with && and ||
• Ternary operator ? : and null coalescing ??
• Switch statement with break and intentional fall-through
• PHP 8's match expression — the safer, cleaner switch

Note: PHP runs on a server. Our examples simulate PHP logic using JavaScript. To run real PHP, install PHP.

🎯 Real-World Analogy: Control flow is like a GPS navigation system. At each junction (condition), the GPS decides which road to take — turn left if the highway is clear, go straight if there's traffic, or take the alternative route. Your code makes similar decisions at every if/else junction.

1️⃣ If / Elseif / Else Syntax

<?php
if ($condition1) {
    // runs if condition1 is true
} elseif ($condition2) {
    // runs if condition2 is true
} else {
    // runs if nothing above was true
}
?>

Key point: PHP uses elseif (one word) or else if (two words) — both work, but elseif is more common.

Try It: If / Elseif / Else

Build a grading system, nested conditions, ternary operator, and combined logic

Try it Yourself »

JavaScript

// PHP Control Flow: if / elseif / else (simulated in JavaScript)
console.log("=== If / Elseif / Else ===");
console.log();

// Grading system
let score = 78;
console.log("Student score: " + score);
console.log();

if (score >= 90) {
    console.log("Grade: A — Excellent! 🌟");
} else if (score >= 80) {
    console.log("Grade: B — Good job! 👍");
} else if (score >= 70) {
    console.log("Grade: C — Satisfactory ✓");
} else if (score >= 60) {
    console.log("Grade: D — Needs improvement");
} el
...

Try It: Switch & Match

Compare switch statement fall-through, PHP 8's match expression, and HTTP status codes

Try it Yourself »

JavaScript

// PHP Switch Statement & Match Expression
console.log("=== Switch Statement ===");
console.log();
console.log("Use switch when comparing one variable against many values.");
console.log("Much cleaner than a long if/elseif chain!");
console.log();

let dayOfWeek = 3;  // 1=Mon, 7=Sun

console.log("Day number: " + dayOfWeek);

// PHP switch statement
switch (dayOfWeek) {
    case 1:
        console.log("Monday — Start of the week 💪");
        break;
    case 2:
        console.log("Tuesday — Kee
...

⚠️ Common Mistakes

⚠️

Missing break in switch — causes unintended fall-through to the next case.

⚠️

Using = instead of == — if ($x = 5) assigns, not compares. Always use == or ===.

⚠️

Truthy/falsy confusion — 0, "", null, "0", and empty arrays are all falsy in PHP.

💡

Pro Tip: Prefer match() over switch in PHP 8+ — no break needed, strict comparison by default, and it returns a value.

📋 Quick Reference — Control Flow

Structure	Use When
if/elseif/else	Different conditions to test
? :	Simple one-line if/else
??	Default value for null
switch	One variable, many values
match()	Like switch but safer (PHP 8+)

🎉 Lesson Complete!

You've mastered PHP control flow! Next, learn how to repeat code with loops.