std::basic_ios<CharT,Traits>:: fill

From cppreference.com
C++
Input/output library
std::basic_ios
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.

Parameters

ch - the character to use as fill character

Return value

The fill character before the call to the function.

Example

Run this code 
#include <iomanip>
#include <iostream>
 
int main ()
{
    std::cout << "With default setting : [" << std::setw(10) << 40 << "]\n";
    char prev = std::cout.fill('x');
    std::cout << "Replaced '" << prev << "' with '"
              << std::cout.fill() << "': [" << std::setw(10) << 40 << "]\n";
}

Output: 

With default setting : [        40]
Replaced ' ' with 'x': [xxxxxxxx40]

See also

changes the fill character
(function template)
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