how to add a ".0" to ostream floats

[Gianni Mariani]

I need to write float values in a specific format.


#include <iostream>
#include <iomanip>

void outdbl( double d )
{
std::cout
<< std::setiosflags(
std::ios_base::showpoint | std::ios_base::right
)
<< std::setprecision(16)
<< d
<< "\n";
}


int main()
{
outdbl( 22.0 );
outdbl( 1.111111111111111111111111 );
}

------------
I would like to see the output be:

22.0
1.111111111111111? ... + whatever the roundoff gives as the last digit


I can't seem to find the incantation if iosflags that that does this.

 

[Denise Kleingeist]

Hello Gianni!

I would like to see the output be:

22.0
1.111111111111111? ... + whatever the roundoff gives as the last digit

Without changing the formatting flags to adapt to the situation, this
will never
happen: you will get 16 digits in either case unless you change the
precision
in cases where you don't want that many trailing zeros. Other than
that,
the formatting flag you are looking for is "fixed".

If you really want the output as indicated above and you really want to
use
simple output to take care of that, you can replace the
std::num_put<char>
facet by a custom facet which does the formatting for you. Of course,
you
still need to write the facet in that case.

Good luck, Denise.