PHP替换字符串中最后一次出现的字符串？

Anyone know of a very fast way to replace the last occurrence of a string with another string in a string?

You can use this function:

function str_lreplace($search, $replace, $subject)
{
    $pos = strrpos($subject, $search);

    if($pos !== false)
    {
        $subject = substr_replace($subject, $replace, $pos, strlen($search));
    }

    return $subject;
}

This will also work:

function str_lreplace($search, $replace, $subject)
{
    return preg_replace('~(.*)' . preg_quote($search, '~') . '(.*?)~', '$1' . $replace . '$2', $subject, 1);
}

UPDATE Slightly more concise version (http://ideone.com/B8i4o):

function str_lreplace($search, $replace, $subject)
{
    return preg_replace('~(.*)' . preg_quote($search, '~') . '~', '$1' . $replace, $subject, 1);
}

$string = 'this is my world, not my world';
$find = 'world';
$replace = 'farm';
$result = preg_replace(strrev("/$find/"),strrev($replace),strrev($string),1);
echo strrev($result); //output: this is my world, not my farm

Another 1-liner but without preg:

$subject = 'bourbon, scotch, beer';
$search = ',';
$replace = ', and';

echo strrev(implode(strrev($replace), explode(strrev($search), strrev($subject), 2))); //output: bourbon, scotch, and beer

Use the "$" on a reg expression to match the end of the string

$string = 'The quick brown fox jumps over the lazy fox';
echo preg_replace('/fox$/', 'dog', $string);

//output
'The quick brown fox jumps over the lazy dog'

The following rather compact solution uses the PCRE positive lookahead assertion to match the last occurrence of the substring of interest, that is, an occurrence of the substring which is not followed by any other occurrences of the same substring. Thus the example replaces the last 'fox' with 'dog'.

$string = 'The quick brown fox, fox, fox jumps over the lazy fox!!!';
echo preg_replace('/(fox(?!.*fox))/', 'dog', $string);

OUTPUT: 

The quick brown fox, fox, fox jumps over the lazy dog!!!

Just one line of code (late answer but it's worth to add it):

$string = 'The quick brown fox jumps over the lazy dog';
$find_me = 'dog';

preg_replace('/'. $find_me .'$/', '', $string);

the ending $ indicates the end of the string.

You could do this:

$str = 'Hello world';
$str = rtrim($str, 'world') . 'John';

Result is 'Hello John';

Regards

You can use strrpos() to find last match.

$string = "picture_0007_value";
$findChar =strrpos($string,"_");

$string[$findChar]=".";

echo $string;

Output : picture_0007.value

$string = "picture_0007_value";
$findChar =strrpos($string,"_");
if($findChar !== FALSE) {
  $string[$findChar]=".";
}

echo $string;

Apart from the mistakes in the code, Faruk Unal has the best anwser. One function does the trick.

Shorthand for accepted answer

function str_lreplace($search, $replace, $subject){ 
    return is_numeric($pos=strrpos($subject,$search))?
    substr_replace($subject,$replace,$pos,strlen($search)):$subject;
}

For the interested: I've written a function that utilises preg_match so that you're able to replace from right hand side using regex.

function preg_rreplace($search, $replace, $subject) {
    preg_match_all($search, $subject, $matches, PREG_SET_ORDER);
    $lastMatch = end($matches);

    if ($lastMatch && false !== $pos = strrpos($subject, $lastMatchedStr = $lastMatch[0])) {
        $subject = substr_replace($subject, $replace, $pos, strlen($lastMatchedStr));
    }

    return $subject;
}

Or as a shorthand combination/implementation of both options:

function str_rreplace($search, $replace, $subject) {
    return (false !== $pos = strrpos($subject, $search)) ?
        substr_replace($subject, $replace, $pos, strlen($search)) : $subject;
}
function preg_rreplace($search, $replace, $subject) {
    preg_match_all($search, $subject, $matches, PREG_SET_ORDER);
    return ($lastMatch = end($matches)) ? str_rreplace($lastMatch[0], $replace, $subject) : $subject;
}

based on https://stackoverflow.com/a/3835653/3017716 and https://stackoverflow.com/a/23343396/3017716

This is an ancient question, but why is everyone overlooking the simplest regexp-based solution? Normal regexp quantifiers are greedy, people! If you want to find the last instance of a pattern, just stick .* in front of it. Here's how:

$text = "The quick brown fox, fox, fox, fox, jumps over etc.";
$fixed = preg_replace("((.*)fox)", "$1DUCK", $text);
print($fixed);

This will replace the last instance of "fox" to "DUCK", like it's supposed to, and print:

The quick brown fox, fox, fox, DUCK, jumps over etc.

A short version:

$NewString = substr_replace($String,$Replacement,strrpos($String,$Replace),strlen($Replace));