PHP Regular Expressions

PHP Regular Expressions (RegEx) – Pattern Matching in PHP

Ever wanted to find a specific word in a sentence, validate an email, or replace text automatically? Well, that’s what Regular Expressions (RegEx) are for!

PHP provides powerful functions to work with RegEx, such as preg_match(), preg_replace(), and preg_match_all(). Let’s break it down with fun examples!

What is a Regular Expression?

A Regular Expression (RegEx) is a pattern that helps match, search, and replace text. Think of it as a **text detective** that finds exactly what you need in a string.

Commonly Used RegEx Functions in PHP

• preg_match() – Finds the first match in a string.
• preg_match_all() – Finds all matches in a string.
• preg_replace() – Replaces matched text with something else.

Example 1: Checking if a String Contains a Word

Let’s check if a string contains the word “PHP”:

<?php
$text = "I love PHP and coding!";
$pattern = "/PHP/";

if (preg_match($pattern, $text)) {
    echo "Match found!";
} else {
    echo "No match found!";
}
?>

Output: “Match found!”

Example 2: Finding All Numbers in a String

Let’s extract all numbers from a string using preg_match_all().

<?php
$text = "I have 2 apples and 5 bananas.";
$pattern = "/\d+/"; // \d+ matches one or more digits

preg_match_all($pattern, $text, $matches);
print_r($matches[0]); // Output: Array ( [0] => 2 [1] => 5 )
?>

This extracts: 2 and 5 from the string.

Example 3: Replacing Text with preg_replace()

Want to replace “apples” with “oranges”? Use preg_replace()!

<?php
$text = "I love apples!";
$pattern = "/apples/";
$replacement = "oranges";

$new_text = preg_replace($pattern, $replacement, $text);
echo $new_text; // Output: I love oranges!
?>

Output: “I love oranges!”

Useful Regular Expressions Patterns

Summary

• RegEx helps find, validate, and replace text efficiently.
• preg_match() finds the first match.
• preg_match_all() finds all matches.
• preg_replace() replaces matched text.

Next Steps

Try experimenting with different patterns to master PHP RegEx!