Strings and Text Handling

PHP strings are byte sequences. Single quotes perform minimal escaping; double quotes and heredoc interpolate. Use mbstring or Intl when characters, locale, or Unicode semantics matter.

Practical example

<?php
$name = trim($input);
$message = sprintf('Hello, %s', $name);
$contains = str_contains($message, 'Hello');
$length = mb_strlen($message, 'UTF-8');

strlen counts bytes. Search, replacement, splitting, joining, and formatting do not escape output. HTML, URLs, headers, SQL, shells, and JSON each require their own contextual APIs. Normalize external encoding at boundaries.