Setfill in c++

Question

What does setfill in c++ do?
Should we always use it with setw?

Answer 1

Armina
It is a manipulator that is used to specify the character to be used as padding when the value/object to be printed isn't wide enough to fill up the width specified by `std::setw` manipulator.

Run this code to see the difference, where padding is added to the left or right.

#include <iostream>
#include <iomanip>

int main()
{
std::cout << "fill left padding\n";
std::cout << std::setfill('*')
<< std::setw(7)
<< 2019;
std::cout << "\nfill right padding\n";
std::cout << std::left
<< std::setfill('*')
<< std::setw(7)
<< 2019;
return 0;
}

Answer 2

Armina
`std::setfill` is meant to be used in tandem with `std::setw`. One defines the padding character, and the other defines the desired width (in characters) for the output.

Seems to me, `std::setfill` doesn't effect without `std::setw`. I didn't understand your idea with the '\t' tab character, can you show me in a code please?

Answer 3

Armina
The tab character '\t' does appear as if it pushes the next data deeper this way. But then we can see that the specified padding character '*' is not being used to pad the output. So I guess they don't get along that well : )

Answer 4

No problem Armina
I'm glad if it helps 👍

Answer 5

Ipang
Thanks , is setfill used always after setw or it can be used after any spaces like"\t"?

Answer 6

#include <iostream >
#include <iomanip >
using namespace std;
int main()
{
cout<<"\t"<<setfill('*')<<2019<< endl;
return 0;
}
I mean instead of using setw for spaces, use " \t "

Answer 7

Thanks Ipang, you helped me alot