In what scenarios can misunderstanding date formats lead to unexpected results in PHP date parsing functions?

Misunderstanding date formats can lead to unexpected results in PHP date parsing functions when the format specified does not match the actual date string provided, causing errors or incorrect output. To avoid this issue, always ensure that the date format used in the parsing function matches the format of the date string being parsed.

// Example of correctly specifying date format to avoid unexpected results
$dateString = '2022-12-31';
$date = DateTime::createFromFormat('Y-m-d', $dateString);
echo $date->format('Y-m-d');