substr() is used to get part of a string. The part of the string to be returned is specified as a range using the start and length arguments.
Behavior of the start and length arguments is interesting, allowing for a great deal of flexibility in choosing what part of the string to replace. See the following table for details.
substr() only operates in a left-to-right fashion. If start is a negative value and length is less than or equal to start , length is considered as having a value of0 instead. For example:
<?php echo substr('Oops!', -2, -4); ?> Output:Oops!
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). The authors of this book have elected not to choose any options under the OPL. This online book was obtained from http://www.fooassociates.com/phpfer/ and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.