Strings & Regex

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

strlen($s);                        // length
str_contains($s, 'World');         // PHP 8+
str_starts_with($s, 'Hello');
str_ends_with($s, '!');
trim($s);                           // strip whitespace
strtolower($s);
str_replace('World', 'PHP', $s);
substr($s, 7, 5);                   // "World"
explode(',', "a,b,c");              // → array
implode('-', ['a','b','c']);       // "a-b-c"
sprintf("%.2f", 3.14159);          // "3.14"
number_format(1234567, 2);         // "1,234,567.00"

// Heredoc (parses variables)
$text = <<<EOT
    Name: $name
    Multiline string here.
EOT;

// Regex (PCRE)
preg_match('/^\d{10}$/', $phone);
preg_match_all('/\b\w+\b/', $text, $matches);
preg_replace('/\s+/', ' ', $text);