S = '2014-10-23 17:56:23:123.5';A = sscanf(S,'%4d-%2d-%2d %2d:%2d:%2d:%f');dstr = sprintf('%4d%2d%2d%2d%2d%2d%5.1f',A);num = str2num(dstr);>> format long>> numnum = 2.014102317562312e+016