PHP Programming

I have been programming in PHP since 2004 when I needed to create a privacy policy module for PHP-Nuke. While I've never been a professional PHP developer, I have enjoyed making websites and tools with it over the years. Despite what some JavaScript developers will have you believe, PHP is not dying, and it is much better than it was in the early 2000s.

This section will cover some basics of PHP programming and also include some notes and code snippets.

What You Need

• PHP 8.1+ installed locally (8.2 or 8.3 is even better)
• A text editor
• Terminal access

Quick local test:

php -v

If you see a version number, you are ready.

Hello World

Create hello.php:

<?php
echo "Hello, World!";

What this does: Prints text to the terminal or browser.

Run it:

php hello.php

Expected output:

Hello, World!

Variables and Basic Types

<?php
$name = "Travis";
$age = 30;
$isAdmin = false;
$height = 5.11;

echo "Name: $name\n";
echo "Age: $age\n";
echo "Height: $height\n";
echo "Admin: " . ($isAdmin ? "yes" : "no") . "\n";

What this does: Stores text, numbers, and booleans in variables and prints them.

Expected output:

Name: Travis
Age: 30
Height: 5.11
Admin: no

If / Else Conditionals

<?php
$score = 87;

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

What this does: Runs one branch based on conditions.

Expected output:

Grade: B

Switch Case

<?php
$status = "pending";

switch ($status) {
    case "new":
        echo "Order created";
        break;
    case "pending":
        echo "Waiting for payment";
        break;
    case "shipped":
        echo "On the way";
        break;
    default:
        echo "Unknown status";
}

What this does: Picks one action from multiple exact values.

Expected output:

Waiting for payment

Loops: for, while, and foreach

<?php
for ($i = 1; $i <= 3; $i++) {
    echo "for: $i\n";
}

$n = 1;
while ($n <= 2) {
    echo "while: $n\n";
    $n++;
}

$langs = ["PHP", "Python", "Bash"];
foreach ($langs as $lang) {
    echo "foreach: $lang\n";
}

What this does: Repeats actions with three common loop styles.

Expected output:

for: 1
for: 2
for: 3
while: 1
while: 2
foreach: PHP
foreach: Python
foreach: Bash

Arrays

<?php
$user = [
    "name" => "NightFox",
    "site" => "nightfox818.com",
    "topics" => ["PHP", "Linux", "Networking"]
];

echo $user["name"] . " runs " . $user["site"] . "\n";
echo "First topic: " . $user["topics"][0];

What this does: Uses associative arrays and nested arrays.

Expected output:

NightFox runs nightfox818.com
First topic: PHP

Functions

<?php
function greet(string $name): string
{
    return "Hello, " . $name . "!";
}

echo greet("World");

What this does: Defines reusable logic and returns a value.

Expected output:

Hello, World!

Match Expression (PHP 8+)

<?php
$httpCode = 404;

$message = match ($httpCode) {
    200 => "OK",
    404 => "Not Found",
    500 => "Server Error",
    default => "Unknown"
};

echo $message;

What this does: Maps input values to output values more cleanly than many chained ifs.

Expected output:

Not Found

Try / Catch Error Handling

<?php
try {
    if (!file_exists("config.php")) {
        throw new Exception("config.php is missing");
    }

    echo "Config loaded";
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}

What this does: Handles exceptions without crashing the whole script.

Expected output (if file is missing):

Error: config.php is missing

Working with Forms

Forms are core PHP workflow. Use POST, validate input, and escape output.

<?php
$name = '';
$message = '';

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $name = trim($_POST['name'] ?? '');

    if ($name === '') {
        $message = 'Please enter your name.';
    } else {
        $safeName = htmlspecialchars($name, ENT_QUOTES, 'UTF-8');
        $message = "Welcome, $safeName.";
    }
}
?>

<form method="post">
    <label for="name">Name:</label>
    <input id="name" name="name" type="text">
    <button type="submit">Submit</button>
</form>

<p><?= $message ?></p>

What this does: Accepts user input, validates it, and safely displays it.

Expected output behavior:

Empty submit: Please enter your name.
Submit "Alex": Welcome, Alex.

Database Access with PDO

Use PDO + prepared statements by default.

<?php
$pdo = new PDO(
    'mysql:host=localhost;dbname=myapp;charset=utf8mb4',
    'dbuser',
    'dbpass',
    [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
    ]
);

$stmt = $pdo->prepare('SELECT id, username FROM users WHERE email = :email');
$stmt->execute(['email' => '[email protected]']);
$user = $stmt->fetch();

if ($user) {
    echo "User ID: " . $user['id'];
} else {
    echo "User not found";
}

What this does: Connects to MySQL safely and queries using a bound parameter.

Expected output behavior:

Matching row: User ID: 123
No row: User not found

Sessions (Login State)

<?php
session_start();

if (!isset($_SESSION['views'])) {
    $_SESSION['views'] = 0;
}

$_SESSION['views']++;
echo "Views this session: " . $_SESSION['views'];

What this does: Persists data across requests for the same visitor.

Expected output behavior:

First refresh: Views this session: 1
Second refresh: Views this session: 2

Useful Built-In Functions

Helpful Code Snippets

Simple Router

<?php
$path = $_SERVER['REQUEST_URI'];
switch ($path) {
    case '/':
        echo "Home page";
        break;
    case '/about':
        echo "About page";
        break;
    default:
        http_response_code(404);
        echo "Page not found";
}

Security note: To avoid path traversal, only use the path for exact matches or sanitize it before using.

Security Checklist

• Always validate and sanitize input
• Escape output with htmlspecialchars() when rendering user data
• Use prepared statements for all SQL queries
• Never store plain text passwords
• Keep PHP and dependencies updated

Next Steps

Build one small app with these pieces:

1. Form input + validation
2. MySQL table + PDO insert/select
3. Session-based login/logout

That one project will lock in most beginner PHP skills quickly.