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strrchr

(PHP 4, PHP 5, PHP 7, PHP 8)

strrchr — 查找指定字符在字符串中的最后一次出现

说明

strrchr(string $haystack, string $needle, bool $before_needle = false): string|false

该函数返回 haystack 字符串中的一部分，这部分以 needle 的最后出现位置开始，直到 haystack 末尾。

参数

haystack

在该字符串中查找。

needle

如果 needle 包含了多个字符，那么仅使用第一个字符。该行为不同于 strstr()。

Prior to PHP 8.0.0, if needle is not a string, it is converted to an integer and applied as the ordinal value of a character. This behavior is deprecated as of PHP 7.3.0, and relying on it is highly discouraged. Depending on the intended behavior, the needle should either be explicitly cast to string, or an explicit call to chr() should be performed.

before_needle

如果为 true，strrchr() 返回最后一次出现 needle 之前的 haystack 部分（不包括 needle）。

返回值

该函数返回字符串的一部分。如果 needle 未被找到，返回 false。

更新日志

版本	说明
8.3.0	新增 `before_needle` 参数。
8.0.0	`needle` 现在接受空字符串。
8.0.0	不再支持将 int 作为 `needle` 传递。
7.3.0	弃用将 int 作为 `needle` 传递。

示例

示例 #1 strrchr() 示例

<?php
$ext = strrchr('somefile.txt', '.');
echo "file extension: $ext \n";
$ext = $ext ? strtolower(substr($ext, 1)) : '';
echo "file extension: $ext";
?>

以上示例的输出类似于：

 
file extension: .txt
file extension: txt

注释

注意: 此函数可安全用于二进制对象。

参见

strstr() - 查找字符串的首次出现
strrpos() - 计算指定字符串在目标字符串中最后一次出现的位置

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User Contributed Notes 10 notes

down

matthewkastor at live dot com ¶

12 years ago

<?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);

}

?>

down

sekati at gmail dot com ¶

17 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);
?>

down

dchris1 at bigpond dot net dot au ¶

19 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/"
?>

down

Primo Anderson Do S?tio ¶

18 years ago

$filename = 'strrchr_test.php';
print strrchr( $filename, '.' );

Result:
.php

$other_filename = 'strrchr_test.asp.php';
print  strrchr( $other_filename, '.' );

Result:
.php

down

readless at gmx dot net ¶

17 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;
   }
}
?>

down

freakinunreal at hotmail dot com ¶

17 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.

down

marcokonopacki at hotmail dot com ¶

20 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)

?>

down

-4

carlos dot lage at gmail dot com ¶

18 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;
} 
?>

down

-5

andfarm at thibs dot menloschool dot org ¶

20 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.

down

-10

alex_bb23 at yahoo.co.uk ¶

6 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...

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