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strrpos

(PHP 4, PHP 5)

strrpos — 计算指定字符串在目标字符串中最后一次出现的位置

说明

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

返回字符串 haystack 中 needle 最后一次出现的数字位置。注意 PHP4 中，needle 只能为单个字符。如果 needle 被指定为一个字符串，那么将仅使用第一个字符。

参数

haystack: 在此字符串中进行查找。
needle: 如果 needle不是一个字符串，它将被转换为整型并被视为字符的顺序值。
offset: 或许会查找字符串中任意长度的子字符串。负数值将导致查找在字符串结尾处开始的计数位置处结束。

返回值

返回 needle 存在的位置。如果没有找到，返回 FALSE 。 Also note that string positions start at 0, and not 1.

Returns FALSE if the needle was not found.

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。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。

更新日志

版本	说明
5.0.0	参数 `needle` 可以是一个多字符的字符串。
5.0.0	引入 `offset` 参数。

范例

Example #1 检查字串是否存在

很容易将“在位置 0 处找到”和“未发现字符串”这两种情况搞错。这是检测区别的办法：

  <?php

$pos  =  strrpos ( $mystring ,  "b" );
if ( $pos  ===  false ) {  // 注意: 三个等号
    // 未发现...
 }

 ?>

Example #2 使用偏移位置进行查找

  <?php
$foo  =  "0123456789a123456789b123456789c" ;

 var_dump ( strrpos ( $foo ,  '7' , - 5 ));   // 从尾部第 5 个位置开始查找
                                   // 结果: int(17)

 var_dump ( strrpos ( $foo ,  '7' ,  20 ));   // 从第 20 个位置开始查找
                                   // 结果: int(27)

 var_dump ( strrpos ( $foo ,  '7' ,  28 ));   // 结果: bool(false)
 ?>

参见

strpos() - 查找字符串首次出现的位置
stripos() - 查找字符串首次出现的位置（不区分大小写）
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）
strrchr() - 查找指定字符在字符串中的最后一次出现
substr() - 返回字符串的子串

用户评论:

[#1] islandispeace at hotmail dot com [2015-11-29 07:30:14]

$offset is very misleading, here is my understanding:

function mystrrpos($haystack, $needle, $offset = 0) {
if ($offset == 0) {
return strrpos ($haystack, $needle);
} else {
return strrpos (substr($haystack, 0, $offset), $needle);
}
}

[#2] info at qrworld dot net [2014-11-04 14:52:36]

I made a function using strrpos to get the extension of a file.

function getExtension($file) {
  $pos = strrpos($file, '.');
  if($pos===false){
    return false;
  } else {
    return substr($file, $pos+1);
  }
}

The link of the post where I took the code is:

http://softontherocks.blogspot.com/2013/07/obtener-la-extension-de-un-fichero-con.html

[#3] tremblay dot jf at gmail dot com [2014-05-12 18:57:48]

I created an easy function that search a substring inside a string.
It reverse the string and the substring inside an strpos and substract the result to the length of the string.

if (!function_exists("real_strrpos")) {
   function real_strrpos($haystack,$needle) {
      $pos  = strlen($haystack);
      $pos -= strpos(strrev($haystack), strrev($needle) );
      $pos -= strlen($needle);
      return $pos;
   }
}

[#4] arlaud pierre [2012-07-02 13:51:28]

This seems to behave like the exact equivalent to the PHP 5 offset parameter for a PHP 4 version.

<?php function strrpos_handmade($haystack, $needle, $offset = 0){ if($offset === 0) return strrpos($haystack, $needle); $length = strlen($haystack); $size = strlen($needle); if($offset < 0) { $virtual_cut = $length+$offset; $haystack = substr($haystack, 0, $virtual_cut+$size); $ret = strrpos($haystack, $needle); return $ret > $virtual_cut ? false : $ret; } else { $haystack = substr($haystack, $offset); $ret = strrpos($haystack, $needle); return $ret === false ? $ret : $ret+$offset; } } ?>

[#5] maxmike at gmail dot com [2009-07-11 22:05:08]

I've got a simple method of performing a reverse strpos which may be of use. This version I have treats the offset very simply:
Positive offsets search backwards from the supplied string index.
Negative offsets search backwards from the position of the character that many characters from the end of the string.

Here is an example of backwards stepping through instances of a string with this function:

<?php function backwardStrpos($haystack, $needle, $offset = 0){ $length = strlen($haystack); $offset = ($offset > 0)?($length - $offset):abs($offset); $pos = strpos(strrev($haystack), strrev($needle), $offset); return ($pos === false)?false:( $length - $pos - strlen($needle) ); } $pos = 0; $count = 0; echo "Test1 "; while(($pos = backwardStrpos("012340567890", "0", $pos)) !== false){ echo $pos." "; $pos--; if($pos < 0){ echo "Done ";break; } } echo "---===--- \nTest2 "; echo backwardStrpos("12341234", "1", 2)." "; echo backwardStrpos("12341234", "1", -2); ?>

Outputs:
Test1
11
5
0
Done
---===---
Test2
0
4

With Test2 the first line checks from the first 3 in "12341234" and runs backwards until it finds a 1 (at position 0)

The second line checks from the second 2 in "12341234" and seeks towards the beginning for the first 1 it finds (at position 4).

This function is useful for php4 and also useful if the offset parameter in the existing strrpos is equally confusing to you as it is for me.

[#6] alexandre at NOSPAM dot pixeline dot be [2008-12-20 08:35:00]

I needed to check if a variable that contains a generated folder name based on user input had a trailing slash.

This did the trick:

<?php // Detect and remove a trailing slash $root_folder = ((strrpos($root_folder, '/') + 1) == strlen($root_folder)) ? substr($root_folder, 0, - 1) : $root_folder; ?>

[#7] dixonmd at gmail dot com [2007-12-24 02:42:15]

<?php $pos = strlen(string $haystack) - strpos (strrev(string $haystack), strrev(string $needle)) - strlen(string $needle); ?>

If in the needle there is more than one character then in php 4 we can use the above statement for finding the position of last occurrence of a substring in a string instead of strrpos. Because in php 4 strrpos uses the first character of the substring.

eg :
<?php $haystack = "you you you you you"; $needle = "you"; $pos1 = strlen($haystack) - strpos (strrev($haystack), strrev($needle)) - strlen($needle); echo $pos1 . " "; $pos2 strrpos($haystack, $needle); echo $pos2 . " "; ?>

[#8] Daniel Brinca [2007-10-15 05:41:05]

Here is a simple function to find the position of the next occurrence of needle in haystack, but searching backwards (lastIndexOf type function):

//search backwards for needle in haystack, and return its position
function rstrpos ($haystack, $needle, $offset){
$size = strlen ($haystack);
$pos = strpos (strrev($haystack), $needle, $size - $offset);

if ($pos === false)
return false;

return $size - $pos;
}

Note: supports full strings as needle

[#9] pb at tdcspace dot dk [2007-09-23 07:26:31]

what the hell are you all doing. Wanna find the *next* last from a specific position because strrpos is useless with the "offset" option, then....

ex: find 'Z' in $str from position $p, backward...

while($p > -1 and $str{$p} <> 'Z') $p--;

Anyone will notice $p = -1 means: *not found* and that you must ensure a valid start offset in $p, that is >=0 and < string length. Doh

[#10] brian at enchanter dot net [2007-07-16 07:47:14]

The documentation for 'offset' is misleading.

It says, "offset may be specified to begin searching an arbitrary number of characters into the string. Negative values will stop searching at an arbitrary point prior to the end of the string."

This is confusing if you think of strrpos as starting at the end of the string and working backwards.

A better way to think of offset is:

- If offset is positive, then strrpos only operates on the part of the string from offset to the end. This will usually have the same results as not specifying an offset, unless the only occurences of needle are before offset (in which case specifying the offset won't find the needle).

- If offset is negative, then strrpos only operates on that many characters at the end of the string. If the needle is farther away from the end of the string, it won't be found.

If, for example, you want to find the last space in a string before the 50th character, you'll need to do something like this:

strrpos($text, " ", -(strlen($text) - 50));

If instead you used strrpos($text, " ", 50), then you would find the last space between the 50th character and the end of the string, which may not have been what you were intending.

[#11] jafet at g dot m dot a dot i dot l dot com [2007-04-12 01:57:59]

Full strpos() functionality, by yours truly.

<?php function conforming_strrpos($haystack, $needle, $offset = 0) { # Why does strpos() do this? Anyway... if(!is_string($needle)) $needle = ord(intval($needle)); $haystack = strval($haystack); # Parameters $hlen = strlen($haystack); $nlen = strlen($needle); # Come on, this is a feature too if($nlen == 0) { trigger_error(__FUNCTION__.'(): Empty delimiter.', E_USER_WARNING); return false; } $offset = intval($offset); $hrev = strrev($haystack); $nrev = strrev($needle); # Search $pos = strpos($hrev, $nrev, $offset); if($pos === false) return false; else return $hlen - $nlen - $pos; } ?>

Note that $offset is evaluated from the end of the string.

Also note that conforming_strrpos() performs some five times slower than strpos(). Just a thought.

[#12] mijsoot_at_gmail_dot_com [2007-03-06 01:43:54]

To begin, i'm sorry for my English.
So, I needed of one function which gives me the front last position of a character.
Then I said myself that it should be better to make one which gives the "N" last position.

$return_context = "1173120681_0__0_0_Mijsoot_Thierry";

// Here i need to find = "Mijsoot_Thierry"

//echo $return_context." ";// -- DEBUG

function findPos($haystack,$needle,$position){
$pos = strrpos($haystack, $needle);
if($position>1){
$position --;
$haystack = substr($haystack, 0, $pos);
$pos = findPos($haystack,$needle,$position);
}else{
// echo $haystack." "; // -- DEBUG
return $pos;
}
return $pos;
}

var_dump(findPos($return_context,"_",2)); // -- TEST

[#13] Christ Off [2007-01-29 10:50:18]

Function to truncate a string
Removing dot and comma
Adding ... only if a is character found

function TruncateString($phrase, $longueurMax = 150) {
$phrase = substr(trim($phrase), 0, $longueurMax);
$pos = strrpos($phrase, " ");
$phrase = substr($phrase, 0, $pos);
if ((substr($phrase,-1,1) == ",") or (substr($phrase,-1,1) == ".")) {
$phrase = substr($phrase,0,-1);
}
if ($pos === false) {
$phrase = $phrase;
}
else {
$phrase = $phrase . "...";
}
return $phrase;
}

[#14] php NO at SPAMMERS willfris SREMMAPS dot ON nl [2006-12-20 18:48:56]

<?php function stringrpos($haystack,$needle,$offset=NULL) { return strlen($haystack) - strpos( strrev($haystack) , strrev($needle) , $offset) - strlen($needle); } // @return -> chopped up for readability. ?>

[#15] purpleidea [2006-11-27 00:07:46]

I was having some issues when I moved my code to run it on a different server.
The earlier php version didn't support more than one character needles, so tada, bugs. It's in the docs, i'm just pointing it out in case you're scratching your head for a while.

[#16] dmitry dot polushkin at gmail dot com [2006-11-03 22:05:49]

Returns the filename's string extension, else if no extension found returns false.
Example: filename_extension('some_file.mp3'); // mp3
Faster than the pathinfo() analogue in two times.
<?php function filename_extension($filename) { $pos = strrpos($filename, '.'); if($pos===false) { return false; } else { return substr($filename, $pos+1); } } ?>

[#17] kavih7 at yahoo dot com [2006-06-08 12:53:10]

<?php ################################################### # # DESCRIPTION: # This function returns the last occurance of a string, # rather than the last occurance of a single character like # strrpos does. It also supports an offset from where to # start the searching in the haystack string. # # ARGS: # $haystack (required) -- the string to search upon # $needle (required) -- the string you are looking for # $offset (optional) -- the offset to start from # # RETURN VALS: # returns integer on success # returns false on failure to find the string at all # ################################################### function strrpos_string($haystack, $needle, $offset = 0) { if(trim($haystack) != "" && trim($needle) != "" && $offset <= strlen($haystack)) { $last_pos = $offset; $found = false; while(($curr_pos = strpos($haystack, $needle, $last_pos)) !== false) { $found = true; $last_pos = $curr_pos + 1; } if($found) { return $last_pos - 1; } else { return false; } } else { return false; } } ?>

[#18] shimon at schoolportal dot co dot il [2006-05-03 11:31:08]

In strrstr function in php 4 there is also no offset.
<?php // by Shimon Doodkin function chrrpos($haystack, $needle, $offset=false) { $needle=$needle[0]; $l=strlen($haystack); if($l==0) return false; if($offset===false) $offset=$l-1; else { if($offset>$l) $offset=$l-1; if($offset<0) return false; } for(;$offset>0;$offset--) if($haystack[$offset]==$needle) return $offset; return false; } ?>

[#19] gordon at kanazawa-gu dot ac dot jp [2005-09-13 21:56:23]

The "find-last-occurrence-of-a-string" functions suggested here do not allow for a starting offset, so here's one, tried and tested, that does:

function my_strrpos($haystack, $needle, $offset=0) {
// same as strrpos, except $needle can be a string
$strrpos = false;
if (is_string($haystack) && is_string($needle) && is_numeric($offset)) {
$strlen = strlen($haystack);
$strpos = strpos(strrev(substr($haystack, $offset)), strrev($needle));
if (is_numeric($strpos)) {
$strrpos = $strlen - $strpos - strlen($needle);
}
}
return $strrpos;
}

[#20] genetically altered mastermind at gmail [2005-08-22 10:30:57]

Very handy to get a file extension:
$this->data['extension'] = substr($this->data['name'],strrpos($this->data['name'],'.')+1);

[#21] fab [2005-08-10 04:07:05]

RE: hao2lian

There are a lot of alternative - and unfortunately buggy - implementations of strrpos() (or last_index_of as it was called) on this page. This one is a slight modifiaction of the one below, but it should world like a *real* strrpos(), because it returns false if there is no needle in the haystack.

<?php function my_strrpos($haystack, $needle) { $index = strpos(strrev($haystack), strrev($needle)); if($index === false) { return false; } $index = strlen($haystack) - strlen($needle) - $index; return $index; } ?>

[#22] jonas at jonasbjork dot net [2005-04-06 01:25:41]

I needed to remove last directory from an path, and came up with this solution:

<?php $path_dir = "/my/sweet/home/"; $path_up = substr( $path_dir, 0, strrpos( $path_dir, '/', -2 ) )."/"; echo $path_up; ?>

Might be helpful for someone..

[#23] escii at hotmail dot com ( Brendan ) [2005-01-10 19:12:44]

I was immediatley pissed when i found the behaviour of strrpos ( shouldnt it be called charrpos ?) the way it is, so i made my own implement to search for strings.

<?php function proper_strrpos($haystack,$needle){ while($ret = strrpos($haystack,$needle)) { if(strncmp(substr($haystack,$ret,strlen($needle)), $needle,strlen($needle)) == 0 ) return $ret; $haystack = substr($haystack,0,$ret -1 ); } return $ret; } ?>

[#24] griffioen at justdesign dot nl [2004-11-17 10:57:26]

If you wish to look for the last occurrence of a STRING in a string (instead of a single character) and don't have mb_strrpos working, try this:

function lastIndexOf($haystack, $needle) {
$index = strpos(strrev($haystack), strrev($needle));
$index = strlen($haystack) - strlen(index) - $index;
return $index;
}

[#25] nexman at playoutloud dot net [2004-10-07 09:22:04]

Function like the 5.0 version of strrpos for 4.x.
This will return the *last* occurence of a string within a string.

function strepos($haystack, $needle, $offset=0) {
$pos_rule = ($offset<0)?strlen($haystack)+($offset-1):$offset;
$last_pos = false; $first_run = true;
do {
$pos=strpos($haystack, $needle, (intval($last_pos)+(($first_run)?0:strlen($needle))));
if ($pos!==false && (($offset<0 && $pos <= $pos_rule)||$offset >= 0)) {
$last_pos = $pos;
} else { break; }
$first_run = false;
} while ($pos !== false);
if ($offset>0 && $last_pos<$pos_rule) { $last_pos = false; }
return $last_pos;
}

If my math is off, please feel free to correct.
- A positive offset will be the minimum character index position of the first character allowed.
- A negative offset will be subtracted from the total length and the position directly before will be the maximum index of the first character being searched.

returns the character index ( 0+ ) of the last occurence of the needle.

* boolean FALSE will return no matches within the haystack, or outside boundries specified by the offset.

[#26] tsa at medicine dot wisc dot edu [2004-05-24 17:17:40]

What the heck, I thought I'd throw another function in the mix. It's not pretty but the following function counts backwards from your starting point and tells you the last occurrance of a mixed char string:

<?php function strrposmixed ($haystack, $needle, $start=0) { // init start as the end of the str if not set if($start == 0) { $start = strlen($haystack); } // searches backward from $start $currentStrPos=$start; $lastFoundPos=false; while($currentStrPos != 0) { if(!(strpos($haystack,$needle,$currentStrPos) === false)) { $lastFoundPos=strpos($haystack,$needle,$currentStrPos); break; } $currentStrPos--; } if($lastFoundPos === false) { return false; } else { return $lastFoundPos; } } ?>

[#27] ZaraWebFX [2003-10-14 11:06:33]

this could be, what derek mentioned:

<?php function cut_last_occurence($string,$cut_off) { return strrev(substr(strstr(strrev($string), strrev($cut_off)),strlen($cut_off))); } // example: cut off the last occurence of "limit" $str = "select delta_limit1, delta_limit2, delta_limit3 from table limit 1,7"; $search = " limit"; echo $str."\n"; echo cut_last_occurence($str,"limit"); ?>

[#28] lee at 5ss dot net [2003-08-29 07:21:10]

I should have looked here first, but instead I wrote my own version of strrpos that supports searching for entire strings, rather than individual characters. This is a recursive function. I have not tested to see if it is more or less efficient than the others on the page. I hope this helps someone!

<?php //Find last occurance of needle in haystack function str_rpos($haystack, $needle, $start = 0){ $tempPos = strpos($haystack, $needle, $start); if($tempPos === false){ if($start == 0){ //Needle not in string at all return false; }else{ //No more occurances found return $start - strlen($needle); } }else{ //Find the next occurance return str_rpos($haystack, $needle, $tempPos + strlen($needle)); } } ?>

[#29] FIE [2003-02-15 05:03:24]

refering to the comment and function about lastIndexOf()...
It seemed not to work for me the only reason I could find was the haystack was reversed and the string wasnt therefore it returnt the length of the haystack rather than the position of the last needle... i rewrote it as fallows:

<?php function strlpos($f_haystack,$f_needle) { $rev_str = strrev($f_needle); $rev_hay = strrev($f_haystack); $hay_len = strlen($f_haystack); $ned_pos = strpos($rev_hay,$rev_str); $result = $hay_len - $ned_pos - strlen($rev_str); return $result; } ?>

this one fallows the strpos syntax rather than java's lastIndexOf.
I'm not positive if it takes more resources assigning all of those variables in there but you can put it all in return if you want, i dont care if i crash my server ;).

~SILENT WIND OF DOOM WOOSH!

[#30] php dot net at insite-out dot com [2002-12-17 11:47:39]

I was looking for the equivalent of Java's lastIndexOf(). I couldn't find it so I wrote this:

<?php function last_index_of($sub_str,$instr) { if(strstr($instr,$sub_str)!="") { return(strlen($instr)-strpos(strrev($instr),$sub_str)); } return(-1); } ?>

It returns the numerical index of the substring you're searching for, or -1 if the substring doesn't exist within the string.

[#31] su.noseelg@naes, only backwards [2002-12-13 10:39:21]

Maybe I'm the only one who's bothered by it, but it really bugs me when the last line in a paragraph is a single word. Here's an example to explain what I don't like:

The quick brown fox jumps over the lazy
dog.

So that's why I wrote this function. In any paragraph that contains more than 1 space (i.e., more than two words), it will replace the last space with ' '.

<?php function no_orphans($TheParagraph) { if (substr_count($TheParagraph," ") > 1) { $lastspace = strrpos($TheParagraph," "); $TheParagraph = substr_replace($TheParagraph," ",$lastspace,1); } return $TheParagraph; } ?>

So, it would change "The quick brown fox jumps over the lazy dog." to "The quick brown fox jumps over the lazy dog." That way, the last two words will always stay together.