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strpos
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strpos

Name

strpos — Finds the first position of a substring within a string.

Synopsis

int strpos(string, substring[, offset]); string string: String to search mixed substring: String to find int offset (optional): Indicates where to start looking

Returns

Integer; FALSE if the substring is not found

Description

strpos() returns the position of the first occurrence of substring within string . If the optional offset parameter is specified, the function starts looking for substring after the specified offset.

If substring is not found, the function returnsFALSE .

If the character parameter is not a string, it's converted to an integer. The resulting integer is used as the ordinal value of a character.

Version

PHP 3+, PHP 4+

Example

Example 1227. Example of a common pitfall when using strpos()

<?php
$string    = 'Jacob Two-Two Meets the Hooded Fang';
$substring = 'Jacob';

// Initialize our position counter
$pos = 0;

// The wrong way to do it - Jacob is found at position 0
// and the while loop exits before running the body of the loop
while ($pos = strpos($string, $substring, $pos)) {
   echo "Found '$substring' at position $pos\n";
   $pos += strlen($substring);
}

// Reinitialize our position counter
$pos = 0;

// A better way to do it - explicitly test for FALSE
// using the strict 'not equals' comparison operator (!==)
while (FALSE !== ($pos = strpos($string, $substring, $pos))) {
   echo "Found '$substring' at position $pos\n";
   $pos += strlen($substring);
}
?>

Output:
Found 'Jacob' at position 0

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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.