Those are some famous place holder:

typedescription
%cRepresents a single character. It is used to read or print a character value.
%sRepresents a string of characters. It is used to read or print a string value.
%fRepresents a floating-point number. It is used to read or print a float value.
%lfRepresents a double-precision floating-point number. It is used to read or print a double value.
%dinteger