$date_string = '2021-08-31 12:00:00'; $timestamp = date2timestamp($date_string); echo $timestamp;This will output the Unix timestamp value corresponding to the given date and time. Some possible package libraries that could include a date2timestamp function are: - DateTime extension - Date and Time functions extension - Date/Time Support extension It's important to note that different libraries may implement this function with slightly different names or arguments, so it's always a good idea to consult the documentation for the specific library being used.