Are there any specific considerations to keep in mind when using regex to replace special characters or symbols in PHP strings, especially when dealing with multiple occurrences?

When using regex to replace special characters or symbols in PHP strings, especially when dealing with multiple occurrences, it's important to be mindful of escape characters and the use of the preg_replace function. To ensure that all occurrences are replaced, you can use the "g" modifier in your regex pattern. Additionally, make sure to properly escape any special characters in your regex pattern to avoid unexpected results.

$string = "This is a string with special characters!@#$";
$pattern = '/[@#$]/';
$replacement = '';
$cleaned_string = preg_replace($pattern, $replacement, $string);
echo $cleaned_string;