sanitize _ *** system function is to escape the input from the outside, and detoxification in a safe form
Also performs validation of as much as possible at the same time
sanitize_num ... numbers (full-width also converted to single-byte)
sanitize_date ... conversion validity of date even in the form of consideration YYY-mm-dd
sanitize_str ... general string to convert
sanitize_asc ... 7bit ASCII code to convert
sanitize_html ... convert the template form of OneThird (escape)