strrchr()

(PHP 4, PHP 5, PHP 7)

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

范例

Example #1strrchr()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";
$last = substr(strrchr($text, 10), 1 );
?>

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

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"
?>

<?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);
}
?>

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);
?>

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;
  }
}
?>

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

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/"
?>

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.

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.

<?
// 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)
?>

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;
} 
?>

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...