teaching_web_development

Introduction to PHP

PHP (Hypertext Preprocessor) is a popular server-side scripting language designed for web development but also used as a general-purpose programming language.

It is especially suited for creating dynamic web pages and applications.

Resources

Slides

Features

Philosophy of PHP

Key Features of PHP

Example PHP Code

<h1> Hello from HTML </h1>

<?php
// This is a simple PHP script that outputs "Hello, World!"
echo "Hello, World!";
?>

<p> This is more HTML content. </p>


Hello from HTML
Hello, World!
This is more HTML content.

Getting Started with PHP

_ Click on “Start” to start the Apache server.

Configuring PHP

<?php
// Your PHP code goes here
echo "Hello World!";
?>

PHP Script

Syntax Basics

<?php
$age = 25; // $age is an integer
$name = "Alice"; // $name is a string
$price = 19.99; // $price is a float
?>

📝 Examples

<?php
// Example 1: Variables and Output
$name = "John";
echo "Hello, " . $name . "!"; // Outputs: Hello, John!
?>

<?php
// Example 2: Conditional Statements
$age = 20;
if ($age >= 18) {
    echo "You are an adult.";
} else {
    echo "You are a minor.";
}
?>

<?php
// Example 3: Looping
for ($i = 1; $i <= 5; $i++) {
    echo "Number: " . $i . "<br>";
}
?>

<?php
// Example 4: Functions
function greet($name) {
    return "Hello, " . $name . "!";
} 

echo greet("Alice"); // Outputs: Hello, Alice!
?>

<?php
// Example 5: Arrays
$fruits = array("Apple", "Banana", "Cherry");
foreach ($fruits as $fruit) {
    echo $fruit . "<br>";
}
?>

Implicit type conversions

<?php
$number = "10"; // string
$sum = $number + 5; // PHP converts $number to an integer
echo $sum; // Outputs: 15
?>

Operators

<?php
$a = 10;
$b = 5; 
$sum = $a + $b; // Addition
$difference = $a - $b; // Subtraction
$product = $a * $b; // Multiplication
$quotient = $a / $b; // Division
$isEqual = ($a == $b); // Comparison
$isGreater = ($a > $b); // Comparison
$andCondition = ($a > 5 && $b < 10); // Logical AND
$orCondition = ($a < 5 || $b < 10); // Logical OR
?>

Increment and Decrement Operators

🎮 Fun Activity 

<?php
$x = 12;
$y = 15 + $x++;
echo "x is $x and y is $y";
$z = 20 + ++$x;
echo "x is $x and y is $y and z is $z";
?>

String concatenation

<?php

$a = "Hello " . "World";
echo $a . "\n";

?>

Side effect assignment

<?php

$x = 10;
$x += 2;
echo $x;

?>

Type casting

<?php

$x = 56;
$y = 12;
echo $x / $y;

?>

Activities: 🎮

<?php

$z = "100" + 36.25 + TRUE;
echo $z;

?>


<?php

echo "100" + (string) 10;

?>

<?php

echo "100" . string(10)

?>

<?php

echo (int) 9.9 - 1.9;

?>

<?php

echo "Soumya" . 25;

?>

<?php

echo "Soumya" + 25;

?>

Equality vs. Identity

<?php
if (123 == "123") print ("Equal \n");

if (123 === "123") print ("Equal \n");
?>

Function return values

Comments

🛠️ Interview with PHP creator

Arrays

<?php
$str_array = array("Hello", "World");
echo $str_array[1];
?>

Array functions

Functions

<?php
include "header.php";
?>

Form processing in PHP

🎮 Practical for PHP forms


<p> Forms in PHP</p>
<form method="post">
  <label>Input guess</label>
    <input type="text" name="guess" id="guess"/>
    <input type="submit">
</form>



<?php
print_r($_POST)
?>

🎮 Full code


<!DOCTYPE html>
<html>
<body>

<?php
$txt = "PHP";
echo "I love $txt!";
?>


<p> Forms in PHP</p>

<form method="post">
  <label>Input guess</label>
    <input type="text" name="guess" id="guess"/>
    <input type="submit">
</form>


<pre>
<?php
print_r($_POST)
?>
</pre>

</body>
</html>

Other input types in forms

Cookies

Sessions

Next: Javascript

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