Re: [Boost-users] [format] print float number with fixed number of decimals *and* integer digits

Subject: Re: [Boost-users] [format] print float number with fixed number of decimals *and* integer digits
From: Larry (lknain_at_[hidden])
Date: 2010-09-30 20:41:42

I believe if you use something like "%015.8lf" you will get more of what you 
want.
I always think that the .8 is the number of digits to the right of decimal 
and the 15
is the entire field width (including sign, any leading zero digits,  any 
digits to the left
of the decimal, the decimal point, and digits to the right of decimal 
point). For
example:

double pi(3.141592);

  format a("%015.8lf");
  a % pi;
  printf("%s\n",a.str().c_str());

prints:

000003.14159200

Larry
----- Original Message ----- 
From: "alfC" <alfredo.correa_at_[hidden]>
To: <boost-users_at_[hidden]>
Sent: Thursday, September 30, 2010 7:21 PM
Subject: [Boost-users] [format] print float number with fixed number of 
decimals *and* integer digits

>I always found the rules for printf formatting, which Boost.Format
> uses, cryptic. I usually find the right combination by trial and
> error. In this case I want to print decimal numbers with both fixed
> number of integer digits and decimal digits. How can I do this with
> Boost.Format.
>
> #include<boost/format.hpp>
> #include<iostream>
> int main(){
>  int i = 2;
>  std::cout << boost::format("%04i") % i << std::endl; //prints 0002,
> ok!
>  double d = 3.1415;
>  std::cout<< boost::format("%04.8f") % d  << std::endl;
>  // ^ prints 3.14150000,
>  //   want   0003.14150000
>  //(or even '   3.14150000')
>  //(or even '   3.1415    ')
>  return 0;
> }
>
> Thank you,
> Alfredo
>
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