🔹 1. What Are Control Structures?

Control structures tell PHP when and how to execute code. They’re the traffic lights of
programming — deciding whether your code should stop, go, or loop back around.

Two main types:

• Conditional statements — make decisions.
• Loops — repeat actions.

🔹 2. Conditional Statements

if / else

Basic decision-making structure:

<?php
$age = 18;

if ($age >= 18) {
    echo "You’re an adult.";
} else {
    echo "You’re a minor.";
}
?>

✅ Output: You’re an adult.

if / elseif / else

For multiple possible outcomes:

<?php
$score = 85;

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

🧠 You can chain as many elseif statements as needed.

switch

Simplifies multiple conditions that compare the same value.

<?php
$day = "Monday";

switch ($day) {
    case "Monday":
        echo "Start of the week!";
        break;
    case "Friday":
        echo "Weekend’s coming!";
        break;
    case "Saturday":
    case "Sunday":
        echo "It’s the weekend!";
        break;
    default:
        echo "Just another weekday.";
}
?>

🧠 Always include break; to stop the switch after a match.

🔹 3. Loops

Loops let you repeat code automatically — perfect for lists, tables, or calculations.

while

Repeats code while a condition is true.

<?php
$count = 1;
while ($count <= 5) {
    echo "Count: $count <br>";
    $count++;
}
?>

✅ Output:

Count: 1
Count: 2
Count: 3
Count: 4
Count: 5

do...while

Runs at least once before checking the condition.

<?php
$num = 1;
do {
    echo "Number: $num <br>";
    $num++;
} while ($num <= 3);
?>

✅ Even if the condition is false, the loop runs once.

for

Commonly used when you know how many times to loop.

<?php
for ($i = 1; $i <= 5; $i++) {
    echo "Iteration $i <br>";
}
?>

🧠 Structure: for (start; condition; increment)

foreach

Used specifically for arrays.

<?php
$colors = ["Red", "Blue", "Green"];

foreach ($colors as $color) {
    echo "$color <br>";
}
?>

✅ Output:

Red
Blue
Green

🔹 4. break and continue

break

Stops a loop early:

<?php
for ($i = 1; $i <= 10; $i++) {
    if ($i == 5) break;
    echo "$i ";
}
// Output: 1 2 3 4
?>

continue

Skips one iteration:

<?php
for ($i = 1; $i <= 5; $i++) {
    if ($i == 3) continue;
    echo "$i ";
}
// Output: 1 2 4 5
?>

🧩 Hands-On Practice

Exercise 1: Odd or Even

Create odd-even.php:

<?php
$number = 7;

if ($number % 2 == 0) {
    echo "$number is even.";
} else {
    echo "$number is odd.";
}
?>

✅ Try changing $number to test different results.

Exercise 2: While Loop Practice

<?php
$count = 1;
while ($count <= 3) {
    echo "This is loop number $count<br>";
    $count++;
}
?>

✅ Observe how it repeats automatically.

Exercise 3: Multiplication Table

Create table.php:

<?php
$number = 5;

for ($i = 1; $i <= 10; $i++) {
    echo "$number x $i = " . ($number * $i) . "<br>";
}
?>

✅ Try different $number values.

Exercise 4: Colors Foreach Loop

<?php
$colors = ["red", "blue", "green", "yellow"];

foreach ($colors as $color) {
    echo "Color: $color <br>";
}
?>

✅ Add or remove colors to see the effect.

Exercise 5: Skip and Stop

<?php
for ($i = 1; $i <= 10; $i++) {
    if ($i == 4) continue;
    if ($i == 8) break;
    echo "$i ";
}
?>

✅ Output should skip 4 and stop before 8.

🎯 Mini Project – Number Guessing Game

Goal: Create an interactive number guessing game.

Create a file guess.php:

<?php
$secret = 7;
$guess = 0;

while ($guess != $secret) {
    $guess = rand(1, 10); // random guess
    echo "Trying $guess...<br>";

    if ($guess == $secret) {
        echo "🎉 Correct! The number was $secret.";
        break;
    }
}
?>

✅ Refresh the page — watch it “guess” until it finds the number.

🧾 Module 4 Quiz

💪 Challenge Task – FizzBuzz Generator

Objective: Combine your understanding of conditionals and loops to solve a famous coding problem.

Create a file fizzbuzz.php:

<?php
for ($i = 1; $i <= 20; $i++) {
    if ($i % 3 == 0 && $i % 5 == 0) {
        echo "FizzBuzz<br>";
    } elseif ($i % 3 == 0) {
        echo "Fizz<br>";
    } elseif ($i % 5 == 0) {
        echo "Buzz<br>";
    } else {
        echo "$i<br>";
    }
}
?>

✅ Output example:

1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz

🧠 This test is a rite of passage for all developers — and you’ve now written it in PHP!

🧾 Submission Checklist

• ✅ odd-even.php → identifies even/odd
• ✅ table.php → displays multiplication table
• ✅ guess.php → number guessing works
• ✅ fizzbuzz.php → correct FizzBuzz logic
• ✅ Quiz answers filled

🏁 Next Step: In Module 5, you’ll move into arrays and PHP’s built-in superglobals, learning how
to store multiple values and handle data from forms — essential for dynamic websites and WordPress development.