#include <iostream>char fill() const;char fill(char ch);
The fill( ) function is a member of ios.
By default, when a field needs to be filled, it is filled with spaces. However, you can specify the fill character using the fill( ) function and specifying the new fill character in ch. The old fill character is returned.
To obtain the current fill character, use the first form of fill( ), which returns the current fill character.
Related functions are precision( ) and width( ).