PHP Cheat Sheet by DaveChild
A quick reference guide for PHP, with functions references, a regular expression syntax guide and a reference for PHP's date formating functions. As of 28/6/14, the cheat sheet now includes popup links to the appropriate PHP manual pages.
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PHP Array Functions
PHP String Functions
PHP Filesystem Functions
PHP Regular Expressions Functions
Regular Expressions Syntax
There's an excellent regular expression tester at: http://regexpal.com/
* PCRE modifier
PHP fopen() Modes
PHP Date Formatting
¹ 0 is Sunday, 6 is Saturday.
² Week that overlaps two years belongs to year that contains most days of that week. Hence week number for 1st January of a given year can be 53 if week belongs to previous year. date("W", mktime(0, 0, 0, 12, 8, $year)) always gives correct number of weeks in $year.
³ The Epoch is the 1st January 1970.
⁴ With leading zeroes