How to Efficiently Replace the Last Occurrence of a String in PHP?

Efficiently Replacing the Last Occurrence of a String

Finding and replacing the last occurrence of a string within a larger string can be a common task in programming. However, the challenge lies in the fact that the last occurrence may not coincide with the final characters in the string.

To address this issue, we present a highly efficient approach that utilizes the PHP functions strrpos() and substr_replace() for precise last-occurrence replacement.

Code Solution:

<code class="php">function str_lreplace($search, $replace, $subject)
{
    $pos = strrpos($subject, $search);

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

    return $subject;
}</code>

Explanation:

The function str_lreplace() takes three parameters: the substring to search for ($search), the replacement substring ($replace), and the original string ($subject).

• strrpos() locates the last occurrence of $search within $subject and returns its position.
• If a match is found ($pos !== false), substr_replace() is invoked to replace a substring of $subject starting at position $pos with a length equal to $search with $replace.
• The modified $subject is then returned.

Example Usage:

To illustrate, let's consider the example provided in the question:

<code class="php">$search = 'The';
$replace = 'A';
$subject = 'The Quick Brown Fox Jumps Over The Lazy Dog';
$result = str_lreplace($search, $replace, $subject);</code>

In this case, the result would be:

The Quick Brown Fox Jumps Over A Lazy Dog

Conclusion:

This approach provides a highly efficient and precise solution for replacing the last occurrence of a string, even if it isn't the last character in the string.

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