PHP Syntax
PHP (Hypertext Preprocessor) is a widely used server-side scripting language designed for web development. Understanding PHP syntax is essential for writing clean, efficient, and functional code. In this guide, we’ll cover all the key aspects of PHP syntax with practical examples.
1. Basic PHP Syntax Structure
A PHP script starts with <?php and ends with ?>. All PHP code must be enclosed within these tags.
Example:
<?php
// PHP code goes here
echo "Hello, World!";
?> Key Points:
- PHP statements end with a semicolon (
;). - The
echostatement outputs text. - Comments can be single-line (
//or#) or multi-line (/* ... */).
2. Variables in PHP
Variables in PHP start with a dollar sign ($) followed by the variable name.
Example:
<?php
$name = "John Doe";
$age = 25;
echo "Name: $name, Age: $age";
?> Rules for PHP Variables:
- Must start with
$followed by a letter or underscore. - Case-sensitive (
$var≠$Var). - No need to declare data types explicitly.
3. Data Types in PHP
PHP supports several data types:
| Data Type | Example |
|---|---|
| String | $text = "Hello"; |
| Integer | $num = 10; |
| Float | $price = 9.99; |
| Boolean | $isTrue = true; |
| Array | $colors = ["Red", "Green"]; |
| NULL | $var = null; |
Example:
<?php
$name = "Alice"; // String
$score = 95; // Integer
$average = 85.5; // Float
$isPassed = true; // Boolean
$subjects = ["Math", "Science"]; // Array
?> 4. Operators in PHP
PHP includes various operators:
Arithmetic Operators
<?php
$a = 10;
$b = 5;
echo $a + $b; // 15
echo $a - $b; // 5
echo $a * $b; // 50
echo $a / $b; // 2
echo $a % $b; // 0
?> Comparison Operators
<?php
$x = 10;
$y = "10";
var_dump($x == $y); // true (value match)
var_dump($x === $y); // false (strict type check)
?> Logical Operators
<?php
$a = true;
$b = false;
var_dump($a && $b); // false (AND)
var_dump($a || $b); // true (OR)
var_dump(!$a); // false (NOT)
?> 5. Conditional Statements
PHP supports if, else, elseif, and switch for decision-making.
Example (if-else):
<?php
$marks = 75;
if ($marks >= 60) {
echo "Passed!";
} else {
echo "Failed!";
}
?> Example (switch):
<?php
$day = "Monday";
switch ($day) {
case "Monday":
echo "Start of the week!";
break;
default:
echo "Another day";
}
?> 6. Loops in PHP
PHP supports for, while, do-while, and foreach loops.
Example (for loop):
<?php
for ($i = 1; $i <= 5; $i++) {
echo "Number: $i <br>";
}
?> Example (foreach loop for arrays):
<?php
$colors = ["Red", "Green", "Blue"];
foreach ($colors as $color) {
echo "$color <br>";
}
?> 7. Functions in PHP
Functions are reusable blocks of code
Example:
<?php
function greet($name) {
return "Hello, $name!";
}
echo greet("John"); // Output: Hello, John!
?> Key Points:
- Functions can accept parameters.
- Use
returnto send back a value.
8. Arrays in PHP
Arrays store multiple values in a single variable.
Indexed Array:
<?php
$fruits = ["Apple", "Banana", "Orange"];
echo $fruits[0]; // Apple
?> Associative Array:
<?php
$person = ["name" => "John", "age" => 30];
echo $person["name"]; // John
?> 9. Superglobal Variables
PHP has predefined global variables like $_GET, $_POST, $_SESSION, etc.
Example (Using $_GET):
<?php
// URL: example.com?name=John
echo "Hello, " . $_GET['name'];
?> 10. Error Handling
Use try-catch for exception handling.
Example:
<?php
try {
$result = 10 / 0;
} catch (Exception $e) {
echo "Error: " . $e->getMessage();
}
?> Conclusion
Understanding PHP syntax is crucial for web development. This guide covered variables, data types, operators, loops, functions, arrays, and error handling.
By mastering these concepts, you can write efficient PHP scripts for dynamic web applications.
