字符串函数
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strripos

(PHP 5)

strripos — 计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）

说明

int strripos ( string $haystack , string $needle [, int $offset = 0 ] )

以不区分大小写的方式查找指定字符串在目标字符串中最后一次出现的位置。与 strrpos() 不同，strripos() 不区分大小写。

参数

haystack

在此字符串中进行查找。

needle

注意 needle 可以是一个单字符或者多字符的字符串。

offset

参数 offset 可以被指定来查找字符串中任意长度的子字符串。

负数偏移量将使得查找从字符串的起始位置开始，到 offset 位置为止。

返回值

返回 needle 最后一次出现的数字位置。注意字符串的起始位置为 0 而非 1。

如果 needle 未被发现，返回 FALSE。

Warning

此函数可能返回布尔值 FALSE，但也可能返回等同于 FALSE 的非布尔值，例如 0 或 ""(空串)。请阅读 布尔类型章节以获取更多信息。应使用 === 运算符 来测试此函数的返回值。

范例

Example #1 strripos() 简单范例

<?php
$haystack = 'ababcd';
$needle   = 'aB';

$pos      = strripos($haystack, $needle);

if ($pos === false) {
    echo "Sorry, we did not find ($needle) in ($haystack)";
} else {
    echo "Congratulations!\n";
    echo "We found the last ($needle) in ($haystack) at position ($pos)";
}
?>

以上例程会输出：

   Congratulations!
   We found the last (aB) in (ababcd) at position (2)

参见

字符串函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）

用户评论:

Anonymous (31-Aug-2010 09:05)

Generally speaking, linear searches are from start to end, not end to start - which makes sense from a human perspective. If you need to find strings in a string backwards, reverse your haystack and needle rather than manually chopping it up.

admin at e-xxi dot net (09-Mar-2010 03:00)

strripos() has very strange behaviour when you provide search position. For some reason it searches forward from the given position, instead of searching backward, that is more logical.

For example if you want to find instanse of $what, previous to the last, strripos($where, $what, $last_what_pos-1) will not wark as expected. It will return $last_what_pos again and again. And that has no sence at all.

To prevent this, I just used $prev_last_what_pos = strripos(substr($where,0,$last_what_pos), $what);

dimmav at in dot gr (25-Sep-2008 05:31)

Suppose you just need a stripos function working backwards expecting that strripos does this job, you better use the following code of a custom function named strbipos:

<?php
function strbipos($haystack="", $needle="", $offset=0) {
// Search backwards in $haystack for $needle starting from $offset and return the position found or false

    $len = strlen($haystack);
    $pos = stripos(strrev($haystack), strrev($needle), $len - $offset - 1);
    return ( ($pos === false) ? false : $len - strlen($needle) - $pos );
}

// Test
$body = "01234Xy7890XYz456xy90";
$str = "xY";
$len = strlen($body);
echo "TEST POSITIVE offset VALUES IN strbipos<br>";
for ($i = 0; $i < $len; $i++) {
    echo "Search in [$body] for [$str] starting from offset [$i]: [" . strbipos($body, $str, $i) . "]<br>";
}
?>

Note that this function does exactly what it says and its results are different comparing to PHP 5 strripos function.

peev[dot]alexander at gmail dot com (20-Apr-2008 10:14)

OK, I guess this will be the final function implementation for PHP 4.x versions ( my previous posts are invalid )

<?php

if(!function_exists("stripos")){
    function stripos(  $str, $needle, $offset = 0  ){
        return strpos(  strtolower( $str ), strtolower( $needle ), $offset  );
    }/* endfunction stripos */
}/* endfunction exists stripos */

if(!function_exists("strripos")){
    function strripos(  $haystack, $needle, $offset = 0  ) {
        if(  !is_string( $needle )  )$needle = chr(  intval( $needle )  );
        if(  $offset < 0  ){
            $temp_cut = strrev(  substr( $haystack, 0, abs($offset) )  );
        }
        else{
            $temp_cut = strrev(    substr(   $haystack, 0, max(  ( strlen($haystack) - $offset ), 0  )   )    );
        }
        if(   (  $found = stripos( $temp_cut, strrev($needle) )  ) === FALSE   )return FALSE;
        $pos = (   strlen(  $haystack  ) - (  $found + $offset + strlen( $needle )  )   );
        return $pos;
    }/* endfunction strripos */
}/* endfunction exists strripos */
?>

peev[dot]alexander at gmail dot com (23-Nov-2007 11:05)

Oops, I forgot to return "false" if the needle is not found. Here is the proper function.

<?php
if(!function_exists("strripos")){
    function strripos($haystack, $needle, $offset=0) {
        if($offset<0){
            $temp_cut = strrev(  substr( $haystack, 0, abs($offset) )  );
        }
        else{
            $temp_cut = strrev(  substr( $haystack, $offset )  );
        }
        $pos = strlen($haystack) - (strpos($temp_cut, strrev($needle)) + $offset + strlen($needle));
        if ($pos == strlen($haystack)) { $pos = 0; }
       
        if(strpos($temp_cut, strrev($needle))===false){
             return false;
        }
        else return $pos;
    }/* endfunction strripos*/
}/* endfunction exists strripos*/
?>

peev[dot]alexander at gmail dot com (18-Oct-2007 01:23)

I think you shouldn't underestimate the length of $needle in the search of THE FIRST POSITION of it's last occurrence in the string. I improved the posted function, with added support for offset. I think this is an exact copy of the real function:

<?php
if(!function_exists("strripos")){
    function strripos($haystack, $needle, $offset=0) {
        if($offset<0){
            $temp_cut = strrev(  substr( $haystack, 0, abs($offset) )  );
        }
        else{
            $temp_cut = strrev(  substr( $haystack, $offset )  );
        }
        $pos = strlen($haystack) - (strpos($temp_cut, strrev($needle)) + $offset + strlen($needle));
        if ($pos == strlen($haystack)) { $pos = 0; }
        return $pos;
    }/* endfunction strripos*/
}/* endfunction exists strripos*/
?>

ElectroFox (02-Aug-2007 09:59)

Sorry, I made that last post a bit prematurely.  One more thing wrong with the simple php4 version is that it breaks if the string is not found.  It should actually look like this:

<?php
if (function_exists('strripos') == false) {
    function strripos($haystack, $needle) {
        $pos = strlen($haystack) - strpos(strrev($haystack), strrev($needle));
        if ($pos == strlen($haystack)) { $pos = 0; }
        return $pos;
    }
}
?>

Note, we now check to see if the $needle was found, and if it isn't, we return 0.

ElectroFox (02-Aug-2007 09:39)

Actually, the above, "Simple way to implement this function in PHP 4" by Yanik Lupien, should be:

<?php
if (function_exists('strripos') == false) {
    function strripos($haystack, $needle) {
        return strlen($haystack) - strpos(strrev($haystack), strrev($needle));
    }
}

?>

Note the reversal (<?php strrev($needle)?>) of the search string.  This was left out in Yanik's example, and without it, you'll simply get the length of the haystack, as the forward string will not likely be found in the reversed haystack.

Thus; if we reverse the haystack, any instance of the search string ($needle) therein will also be reversed, so we must reverse it to look for it. :)

Yanik Lupien (03-Jul-2007 06:47)

Simple way to implement this function in PHP 4

<?php
if (function_exists('strripos') == false) {
    function strripos($haystack, $needle) {
        return strlen($haystack) - strpos(strrev($haystack), $needle);
    }
}

?>

aidan at php dot net (30-May-2004 06:36)

This functionality is now implemented in the PEAR package PHP_Compat.

More information about using this function without upgrading your version of PHP can be found on the below link:

http://pear.php.net/package/PHP_Compat