std::basic_ios::fill

From cppreference.com
CharT fill() const;
(1)
CharT fill( CharT ch );
(2)

Manages the fill character used to pad the output conversions to the specified field width.

1) returns the current fill character

2) sets the fill character to ch, returns previous value of the fill character

[edit] Parameters

ch - the character to use as fill character

[edit] Return value

the fill character before the call to the function.

[edit] Example