What are common errors to watch out for when using preg_match in PHP?

Common errors to watch out for when using preg_match in PHP include not escaping special characters in the regular expression pattern, not handling errors or returning false when the function fails, and not properly validating the input data before using preg_match. To solve these issues, always escape special characters in the regular expression pattern using preg_quote, check for errors using === false, and validate input data before passing it to preg_match. 

// Example code snippet demonstrating the correct usage of preg_match

$pattern = '/^([a-zA-Z0-9\s]+)$/';
$input = $_POST['input'];

if(preg_match(preg_quote($pattern), $input) === 1) {
    echo "Input is valid.";
} else {
    echo "Input is invalid.";
}

Keywords

preg_match PHP regular expressions error handling validation

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