String Functions
PHP has a rich set of built-in string functions for manipulation and formatting.
Example
<?php
$text = "Hello, World!";
echo strlen($text); // 13
echo strtoupper($text); // "HELLO, WORLD!"
echo strtolower($text); // "hello, world!"
echo substr($text, 0, 5); // "Hello"
echo str_replace("World", "PHP", $text); // "Hello, PHP!"
echo strpos($text, "World"); // 7
echo trim(" hello "); // "hello"
echo str_repeat("*", 5); // "*****"
echo ucfirst("hello world"); // "Hello world"
echo ucwords("hello world"); // "Hello World"
// String interpolation (double quotes only)
$name = "Alice";
echo "Hello, $name!"; // "Hello, Alice!"
echo "Age: {$user['age']}"; // with complex expressions
echo 'No $interpolation'; // literal: 'No $interpolation'
// Heredoc
$html = <<<HTML
<div>
<h1>Hello, $name</h1>
</div>
HTML;
?>