Return the line number that contains the character at byte count {byte} in the current buffer. This includes the end-of-line character, depending on the 'fileformat' option for the current buffer. The first character has byte count one. Also see line2byte(), go and :goto.

Returns -1 if the {byte} value is invalid.

Can also be used as a method:

GetOffset()->byte2line()

not available when compiled without the +byte_offset feature