%s means print a string argument. Actually, prints any object, with `princ'.
%d means print as signed number in decimal.
-%o means print as unsigned number in octal, %x as unsigned number in hex.
+%o means print as unsigned number in octal.
+%x means print as unsigned number in hex.
%X is like %x, but uses upper case.
%e means print a number in exponential notation.
%f means print a number in decimal-point notation.