PHP Strings

<?php
$name = "Alice";

// Single quotes — literal
echo 'Hello $name';       // Hello $name

// Double quotes — parses variables
echo "Hello $name";       // Hello Alice
echo "Tab:\there";        // Tab:    here

// Heredoc — like double quotes, multi-line
$text = <<<EOT
Hello $name,
Welcome to PHP!
EOT;
echo $text;

// Nowdoc — like single quotes, multi-line
$raw = <<<'EOT'
Hello $name,
No variable parsing here.
EOT;
echo $raw;
?>

<?php
$str = "  Hello, World!  ";

echo strlen($str);              // 18 (includes spaces)
echo strtoupper($str);          // "  HELLO, WORLD!  "
echo strtolower($str);          // "  hello, world!  "
echo trim($str);                // "Hello, World!"
echo ltrim($str);               // "Hello, World!  "
echo rtrim($str);               // "  Hello, World!"

$clean = trim($str);
echo str_replace("World", "PHP", $clean); // Hello, PHP!
echo strpos($clean, "World");             // 7
echo substr($clean, 7, 5);               // World
echo str_repeat("ab", 3);               // ababab
echo str_word_count($clean);             // 2
echo ucfirst("hello world");             // Hello world
echo ucwords("hello world");             // Hello World
echo strrev("PHP");                      // PHP reversed: PHP
?>

<?php
// explode / implode
$csv = "apple,banana,cherry";
$fruits = explode(",", $csv);
print_r($fruits); // Array ( [0] => apple [1] => banana [2] => cherry )

$joined = implode(" | ", $fruits);
echo $joined; // apple | banana | cherry

// sprintf — formatted string
$price = 9.5;
echo sprintf("Price: $%.2f", $price); // Price: $9.50

// number_format
echo number_format(1234567.891, 2, '.', ','); // 1,234,567.89

// String padding
echo str_pad("5", 3, "0", STR_PAD_LEFT); // 005

// Check if substring exists (PHP 8)
echo str_contains("Hello World", "World") ? "found" : "not found"; // found
echo str_starts_with("Hello", "He") ? "yes" : "no"; // yes
echo str_ends_with("Hello", "lo") ? "yes" : "no";   // yes
?>