What are the potential limitations or restrictions when using lookbehinds in PHP regex patterns?

Lookbehinds in PHP regex patterns have certain limitations, such as not supporting variable length lookbehinds or lookbehinds that contain quantifiers. To work around these limitations, you can use fixed length lookbehinds or alternative approaches like capturing groups. 

// Example of using a fixed length lookbehind to match a pattern
$string = "abc123";
if (preg_match('/(?<=abc)\d+/', $string, $matches)) {
    echo "Match found: " . $matches[0];
} else {
    echo "No match found";
}

Keywords

lookbehinds limitations restrictions PHP regex patterns

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