How can the use of modifiers like "m" in preg_match() impact the outcome of a regular expression search in PHP?

Using modifiers like "m" in preg_match() can impact the outcome of a regular expression search in PHP by changing the behavior of certain metacharacters like "^" and "$" to match the beginning and end of each line in a multi-line string, rather than the entire string. This can be useful when working with multi-line strings to ensure that the regular expression matches only at the beginning or end of each line. 

// Using the "m" modifier in preg_match to match the beginning of each line in a multi-line string
$pattern = '/^start/m';
$string = "start\nmiddle\nstart";
if(preg_match($pattern, $string)){
    echo "Match found!";
} else {
    echo "No match found.";
}

Keywords

PHP preg_match() modifiers regular expression search

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