php教程

strrchr

(PHP 4, PHP 5, PHP 7)

strrchr查找指定字符在字符串中的最后一次出现

说明

strrchr ( string $haystack , mixed $needle ) : string

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 包含了不止一个字符,那么仅使用第一个字符。该行为不同于 strstr()

如果 needle 不是一个字符串,那么将被转化为整型并被视为字符顺序值。

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
4.3.0 该函数是二进制安全的。

范例

Example #1 strrchr() 范例

<?php
// 获取 $PATH 中不含磁盘符号的目录
$dir substr(strrchr($PATH":"), 1);

// 获取最后一行内容
$text "Line 1\nLine 2\nLine 3";
$last substr(strrchr($text10), );
?>

注释

Note: 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

User Contributed Notes

alex_bb23 at yahoo.co.uk 02-Aug-2017 08:32
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...
jphansen at uga dot edu 15-Aug-2012 04:16
To extract your portion of a string without the actual character you searched for, you can use:

<?php
$path
= '/www/public_html/index.html';
$filename = substr(strrchr($path, "/"), 1);
echo
$filename; // "index.html"
?>
matthewkastor at live dot com 30-Mar-2011 01:07
<?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);
}
?>
readless at gmx dot net 06-Jun-2006 07:55
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;
   }
}
?>
sekati at gmail dot com 08-Apr-2006 05:43
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);
?>
freakinunreal at hotmail dot com 24-Dec-2005 10:54
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.
29-Jul-2005 10:24
$filename = 'strrchr_test.php';
print strrchr( $filename, '.' );

Result:
.php

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

Result:
.php
carlos dot lage at gmail dot com 03-Apr-2005 11:45
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;
}
?>
dchris1 at bigpond dot net dot au 16-Feb-2004 07:16
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/"
?>
andfarm at thibs dot menloschool dot org 23-May-2003 04:24
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.
marcokonopacki at hotmail dot com 14-Apr-2003 12:43
<?

// 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)

?>

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