Re: Getting equivalent 'double' parsing in c++ and fortran?

[Tobias Schlüter <tobias dot schlueter at physik dot uni-muenchen dot de>]

Convey, Christian J CIV NUWC NWPT wrote:

> The two programs printed out these numbers to stdout.  (The ellipses
> didn't appear in the actual output.  They show where I didn't want to
> type any more numerals.) :
>
> 2.70000000000000017762568294...  (c++) 
> 2.70000000000000017762570000...  (fortran)
>
>
> Assuming that the two programs really are using two different
> double-precision numbers to record "2.7", does anyone know what I can
> do to the C++ code so that, when parsing strings to doubles, it will
> get the same double-precision number that the fortran code yields?

Those two decimal strings represent the same binary number.  gfortran's 
library uses an algorithm which will print the shortest string of 
non-zero digits that will exactly represent the binary number, that's 
why it stops where your C library doesn't.

Hope this helps,
- Tobi