By using this site, you agree to our updated Privacy Policy and our Terms of Use. Manage your Cookies Settings.
446,194 Members | 847 Online
Bytes IT Community
+ Ask a Question
Need help? Post your question and get tips & solutions from a community of 446,194 IT Pros & Developers. It's quick & easy.

NaN question

P: n/a
How do i write an if statement that checks the results of a operation
to see if its nan (not a number) or not? *using g++, a linux complier*

I tried
double x;
if (x == nan)
{
code here
}

but nan isnt a built in defined varible.
I cant say:
if (x == 0)
because that means it holds a value of a number.

I am performing a complex mathimatical equation on diffrent variables
and need to create a if statement for the times that my equation
returns NaN.

Thanks!
-Cephas
Jul 22 '05 #1
Share this Question
Share on Google+
3 Replies


P: n/a

"Cephas" <ce******@lycos.com> wrote in message
news:59************************@posting.google.com ...
How do i write an if statement that checks the results of a operation
to see if its nan (not a number) or not? *using g++, a linux complier*

I tried
double x;
if (x == nan)
{
code here
}

but nan isnt a built in defined varible.
I cant say:
if (x == 0)
because that means it holds a value of a number.

I am performing a complex mathimatical equation on diffrent variables
and need to create a if statement for the times that my equation
returns NaN.

Thanks!
-Cephas


there should be an isnan or isNaN function kicking around somewhere that you
can use to test a given value

Tom
Jul 22 '05 #2

P: n/a
ce******@lycos.com (Cephas) wrote in message news:<59************************@posting.google.co m>...
How do i write an if statement that checks the results of a operation
to see if its nan (not a number) or not? *using g++, a linux complier*


//...
#include <math.h>
//...
if( isnan(0/0) )
cout << "0/0 = nan" << endl;
else
cout << "0/0 = " << (0/0) << endl;

Try
man isnan
for isinf() and finite().
Jul 22 '05 #3

P: n/a

"Cephas" <ce******@lycos.com> wrote in message news:59************************@posting.google.com ...

In the C header math.h (or cmath in C++) there is a macro called isnan.
Jul 22 '05 #4

This discussion thread is closed

Replies have been disabled for this discussion.