Strings and Regex

Form fields, URLs, headers, CSV rows and database columns all reach PHP as strings. A PHP string is a sequence of bytes with no encoding attached, and the classic functions (strlen(), substr(), strtoupper()) work on bytes: exact for ASCII, wrong for "café" or "日本". The mb_* functions count characters instead, the grapheme_* functions count what a reader sees, and the preg_* functions add the PCRE2 regular-expression engine.

Subsections

• String Literals
• Interpolation
• Length, Substrings and Slicing
• Searching Within Strings
• Replacing and Rewriting
• Splitting and Joining
• Case, Trimming and Wrapping
• Comparing and Sorting Strings
• printf and Formatting
• Multibyte Strings
• HTML-Safe Output and Escaping
• PCRE Patterns
• Using PCRE