C++ IOS Library - fill

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Description

It is used to get/set fill character. The fill character is the character used by output insertion functions to fill spaces when padding results to the field width.

Declaration

Following is the declaration for ios::fill function.

get (1)	 char fill() const;
set (2)	 char fill (char fillch);

The above first form (1) returns the fill character.

The above second form (2) sets fillch as the new fill character and returns the fill character used before the call.

Parameters

fillch − The new fill character.

Return Value

The value of the fill character before the call.

Exceptions

Basic guarantee − if an exception is thrown, the stream is in a valid state.

Data races

Accesses (1) or modifies (2) the stream object.

Concurrent access to the same stream object may cause data races.

Example

In below example explains about ios::fill function.

#include <iostream>     

int main () {
   char prev;

   std::cout.width (10);
   std::cout << 40 << '\n';

   prev = std::cout.fill ('x');
   std::cout.width (10);
   std::cout << 40 << '\n';

   std::cout.fill(prev);

   return 0;
}

Let us compile and run the above program, this will produce the following result −

 40
xxxxxxxx40