What common error can occur when using preg_match_all in PHP?

When using preg_match_all in PHP, a common error that can occur is not checking if the function call was successful before using the results. This can lead to unexpected behavior or errors if the regex pattern does not match anything in the input string. To solve this issue, it is important to check the return value of preg_match_all to ensure that the function call was successful before attempting to use the results.

// Example code snippet to check if preg_match_all was successful before using the results
$input = "Hello, World!";
$pattern = "/\b\w+\b/";
if (preg_match_all($pattern, $input, $matches)) {
    // Use the $matches array here
    print_r($matches);
} else {
    echo "No matches found.";
}