note 92705 added to function.str-pad

I am learning PHP right now, and I am confused about something...some of the string functions use underscores in the naming and others do not (str_pad vs. substr for example), is there a rule of thumb as to which are which so I can remember the syntax without looking it up ? ---- Server IP: 209.41.74.194 Probable Submitter: 209.232.112.211 ---- Manual Page -- http://www.php.net/manual/en/function.str-pad.php Edit -- https://master.php.net/note/edit/92705 Del: integrated -- https://master.php.net/note/delete/92705/integrated Del: useless -- https://master.php.net/note/delete/92705/useless Del: bad code -- https://master.php.net/note/delete/92705/bad+code Del: spam -- https://master.php.net/note/delete/92705/spam Del: non-english -- https://master.php.net/note/delete/92705/non-english Del: in docs -- https://master.php.net/note/delete/92705/in+docs Del: other reasons-- https://master.php.net/note/delete/92705 Reject -- https://master.php.net/note/reject/92705 Search -- https://master.php.net/manage/user-notes.php