Re: [c++] problem a function

From:

Victor Bazarov <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Tue, 03 Mar 2009 17:45:56 -0500

Message-ID:

<gokbv5$krs$1@news.datemas.de>

ZikO wrote:

I recently made a little program which generates ASCII file for another
program. One of the functions there generates number and returns that as
double:

double getNumber(...) {
// code
return double(...);
}

If in the function something goes wrong I return 0.0. Although it's
working for my little program very well I found that I might need 0 as a
proper returned value. What am I supposed to do to "inform"/indicate
that something is wrong in function if it can return everything even 0?

Another way is to return NaN (not a number), see if your library
implements 'std::numeric_limits<double>::quiet_NaN()' function (it is
usually indicated by 'std::numeric_limits<double>::has_quiet_NaN'
expression which yields bool. So, something like

     double getNumber (...

        // when something is wrong
        if (std::numeric_limits<double>::has_quiet_NaN)
           return std::numeric_limits<double>::quiet_NaN();
        else
           throw "Something is not right";
    }

There is also infinity...

V
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