<?php
/**
* Removes the preceeding or proceeding portion of a string
* relative to the last occurrence of the specified character.
* The character selected may be retained or discarded.
*
* Example usage:
* <code>
* $example = 'http://example.com/path/file.php';
* $cwd_relative[] = cut_string_using_last('/', $example, 'left', true);
* $cwd_relative[] = cut_string_using_last('/', $example, 'left', false);
* $cwd_relative[] = cut_string_using_last('/', $example, 'right', true);
* $cwd_relative[] = cut_string_using_last('/', $example, 'right', false);
* foreach($cwd_relative as $string) {
* echo "$string <br>".PHP_EOL;
* }
* </code>
*
* Outputs:
* <code>
* http://example.com/path/
* http://example.com/path
* /file.php
* file.php
* </code>
*
* @param string $character the character to search for.
* @param string $string the string to search through.
* @param string $side determines whether text to the left or the right of the character is returned.
* Options are: left, or right.
* @param bool $keep_character determines whether or not to keep the character.
* Options are: true, or false.
* @return string
*/
function cut_string_using_last($character, $string, $side, $keep_character=true) {
$offset = ($keep_character ? 1 : 0);
$whole_length = strlen($string);
$right_length = (strlen(strrchr($string, $character)) - 1);
$left_length = ($whole_length - $right_length - 1);
switch($side) {
case 'left':
$piece = substr($string, 0, ($left_length + $offset));
break;
case 'right':
$start = (0 - ($right_length + $offset));
$piece = substr($string, $start);
break;
default:
$piece = false;
break;
}
return($piece);
}
?>
strrchr
(PHP 4, PHP 5, PHP 7, PHP 8)
strrchr — 文字列中に文字が最後に現れる場所を取得する
説明
この関数は、文字列 haystack の中で
needle が最後に現れた位置から、
haystack の終わりまでを返します。
パラメータ
-
haystack -
検索対象の文字列。
-
needle -
needleがひとつ以上の文字を含んでいる場合は、 最初のもののみが使われます。この動作は、 strstr() とは異なります。PHP 8.0.0 より前のバージョンでは、
needleが文字列でない場合、 数値に変換され、文字の通常の値として扱われていました。 この振る舞いは PHP 7.3.0 以降では推奨されないので、 この機能を使用しないことを強く推奨します。 意図した動作に依存する場合、needleを string に明示的にキャストするか、 明示的に chr() 関数を呼び出すべきでしょう。 -
before_needle -
trueにすると、haystackの中で 最後にneedleが現れる箇所より前の部分を返します (needle は含めません)。
戻り値
この関数は、部分文字列を返します。
needle が見つからない場合は false を返します。
変更履歴
| バージョン | 説明 |
|---|---|
| 8.3.0 |
before_needle が追加されました。
|
| 8.0.0 |
needle は、空文字列を受け入れるようになりました。
|
| 8.0.0 |
needle に数値を渡すことはサポートされなくなりました。
|
| 7.3.0 |
needle に数値を渡すことは非推奨になりました。
|
例
例1 strrchr() の例
<?php
$ext = strrchr('somefile.txt', '.');
echo "file extension: $ext \n";
$ext = $ext ? strtolower(substr($ext, 1)) : '';
echo "file extension: $ext";
?>上の例の出力は、 たとえば以下のようになります。
file extension: .txt file extension: txt
注意
注意: この関数はバイナリデータに対応しています。
add a note
User Contributed Notes 10 notes
matthewkastor at live dot com ¶
13 years ago
sekati at gmail dot com ¶
18 years ago
just a small addition to carlos dot lage at gmail dot com note which makes it a bit more useful and flexible:
<?php
// return everything up to last instance of needle
// use $trail to include needle chars including and past last needle
function reverse_strrchr($haystack, $needle, $trail) {
return strrpos($haystack, $needle) ? substr($haystack, 0, strrpos($haystack, $needle) + $trail) : false;
}
// usage:
$ns = (reverse_strrchr($_SERVER["SCRIPT_URI"], "/", 0));
$ns2 = (reverse_strrchr($_SERVER["SCRIPT_URI"], "/", 1));
echo($ns . "<br>" . $ns2);
?>
dchris1 at bigpond dot net dot au ¶
20 years ago
The function provided by marcokonopacki at hotmail dot com isn't really a reverse-version of strrchr(), rather a reverse version of strchr(). It returns everything from the start of $haystack up to the FIRST instance of the $needle. This is basically a reverse of the behavior which you expect from strchr(). A reverse version of strrchr() would return everything in $haystack up to the LAST instance of $needle, eg:
<?php
// reverse strrchr() - PHP v4.0b3 and above
function reverse_strrchr($haystack, $needle)
{
$pos = strrpos($haystack, $needle);
if($pos === false) {
return $haystack;
}
return substr($haystack, 0, $pos + 1);
}
?>
Note that this function will need to be modified slightly to work with pre 4.0b3 versions of PHP due to the return type of strrpos() ('0' is not necessarily 'false'). Check the documentation on strrpos() for more info.
A function like this can be useful for extracting the path to a script, for example:
<?
$string = "/path/to/the/file/filename.php";
echo reverse_strrchr($string, '/'); // will echo "/path/to/the/file/"
?>
Primo Anderson Do S?tio ¶
19 years ago
$filename = 'strrchr_test.php';
print strrchr( $filename, '.' );
Result:
.php
$other_filename = 'strrchr_test.asp.php';
print strrchr( $other_filename, '.' );
Result:
.php
readless at gmx dot net ¶
18 years ago
to: repley at freemail dot it
the code works very well, but as i was trying to cut script names (e.g.: $_SERVER["SCRIPT_NAME"] => /index.php, cut the string at "/" and return "index.php") it returned nothing (false). i've modified your code and now it works also if the needle is the first char.
- regards from germany
<?php
//strxchr(string haystack, string needle [, bool int leftinclusive [, bool int rightinclusive ]])
function strxchr($haystack, $needle, $l_inclusive = 0, $r_inclusive = 0){
if(strrpos($haystack, $needle)){
//Everything before last $needle in $haystack.
$left = substr($haystack, 0, strrpos($haystack, $needle) + $l_inclusive);
//Switch value of $r_inclusive from 0 to 1 and viceversa.
$r_inclusive = ($r_inclusive == 0) ? 1 : 0;
//Everything after last $needle in $haystack.
$right = substr(strrchr($haystack, $needle), $r_inclusive);
//Return $left and $right into an array.
return array($left, $right);
} else {
if(strrchr($haystack, $needle)) return array('', substr(strrchr($haystack, $needle), $r_inclusive));
else return false;
}
}
?>
freakinunreal at hotmail dot com ¶
18 years ago
to marcokonopacki at hotmail dot com.
I had to make a slight change in your function for it to return the complete needle inclusive.
// Reverse search of strrchr.
function strrrchr($haystack,$needle)
{
// Returns everything before $needle (inclusive).
//return substr($haystack,0,strpos($haystack,$needle)+1);
// becomes
return substr($haystack,0,strpos($haystack,$needle)+strlen($needle));
}
Note: the +1 becomes +strlen($needle)
Otherwise it only returns the first character in needle backwards.
marcokonopacki at hotmail dot com ¶
21 years ago
<?
// Reverse search of strrchr.
function strrrchr($haystack,$needle)
{
// Returns everything before $needle (inclusive).
return substr($haystack,0,strpos($haystack,$needle)+1);
}
$string = "FIELD NUMBER(9) NOT NULL";
echo strrrchr($string,")"); // Will print FIELD (9)
?>
carlos dot lage at gmail dot com ¶
19 years ago
I used dchris1 at bigpond dot net dot au 's reverse strrchr and reduced it to one line of code and fixed it's functionality - the real strrchr() returns FALSE if the needle is not found, not the haystack :)
<?php
// reverse strrchr()
function reverse_strrchr($haystack, $needle)
{
return strrpos($haystack, $needle) ? substr($haystack, 0, strrpos($haystack, $needle) +1 ) : false;
}
?>
andfarm at thibs dot menloschool dot org ¶
21 years ago
strrchr is also very useful for finding the extension of a file. For example:
$ext = strrchr($filename, ".");
and $ext will contain the extension of the file, including a ".", if the file has an extension, and FALSE if the file has no extension. If the file has multiple extensions, such as "evilfile.jpg.vbs", then this construction will just return the last extension.
alex_bb23 at yahoo.co.uk ¶
7 years ago
I think that a good way (I don't know if is the best one) to extract a portion from a string:
<?php
$image = "image.name.jpg";
// get file extension
preg_replace("/.*\.(.*)$/", "$1", $last);
// will result: jpg
?>
Is faster that substr(strrchr...
