01 Avoid using regex whenever possible.md

Avoid using regex whenever possible

Let's face it, regex is hard. So avoid using them whenever possible. Just to name a few cases where you should absolutely avoid them with a suitable alternative solution:

• Validating number ranges: use php comparison operators
• Validating email addresses: use filter_var() with FILTER_VALIDATE_EMAIL and/or send an email already*
• Validating IP addresses: use filter_var() with FILTER_VALIDATE_IP
• Validating URLs: use filter_var() with FILTER_VALIDATE_URL*
• Validating dates: see this Stack Overflow thread
• Parsing JSON: use json_decode()
• Parsing HTML / XML: use a dedicated parser. See How do you parse and process HTML/XML in PHP?
• Parsing CSV: use str_getcsv() or fgetcsv()
• Parsing complex grammars: there's almost always a dedicated parser for your favourite language
• Check if string contains substring: use strpos or stripos

A few other cases you might consider avoiding:

• Name validation: read about Falsehoods Programmers Believe About Names
• Address validation: read about Falsehoods programmers believe about addresses

* It might not work with internationalized domains and email addresses. See top comments at the documentation.

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