Need an explaination of using a " do, while" loop for end of file

I'm using a while loop to take in information from a .dat until it reaches the end of the file, everything is working right
except that it adds an extra input from the file,
(there is a list of say 10 pairs of numbers, reads and computes them, displays the computions, but displays 11 computions, this should only be 10)

here is the way I have my loop set up
do
{

}
while (infile);

any suggestions for revising?

thanks for the help
LVL 1
Orlando15767Asked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

mnashadkaCommented:
If doesn't reach the end of the file until you try to read the last time, so:
do
{
  infile >> myvar;
  process(myvar);
} while(infile);
Will fail the last time with infile >> myvar, but you don't check it until after process is called the last time.  You might want to change it to something like:
while(infile >> myvar)
{
  process(myvar);
}

Good luck.
0
Orlando15767Author Commented:
tried that and it is still giveing me and extra computation.

thanks for the help
0
mnashadkaCommented:
That works for me.  Could you post more code so that we can help you better?  Also, what is the format of the file?
0
Cloud Class® Course: Microsoft Azure 2017

Azure has a changed a lot since it was originally introduce by adding new services and features. Do you know everything you need to about Azure? This course will teach you about the Azure App Service, monitoring and application insights, DevOps, and Team Services.

Orlando15767Author Commented:
here is the whole loop, the files are .dat

while (infile)
{
            //outfile << "Enter first integer ";
            infile >> m;
            outfile << "\nThe first integer is: " << m << endl;
            //outfile << "Enter second integer ";
            infile >> n;
            outfile << "The second integer is: " << n << endl;
            
      if (m < n)
      {
            ntemp = n;
            mtemp = m;
            m = ntemp;
            n = mtemp;
      }
      
            r = n % m;
            while(r != 0)
      {
            n = m;
            m = r;
            r = n % m;
      }
      

            outfile << "\nThe GCD is: " << m << endl;
            outfile << "\n";
            outfile << "\n";
}
0
mnashadkaCommented:
You're running into the same problem that I described earlier.  infile when cast to a bool (technically cast to a void *) only fails when it reaches the end of file condition, and you're not reaching end of file until you do infile >> m;  Change it to:
while(infile >> m)
{
         outfile << "\nThe first integer is: " << m << endl;
          //outfile << "Enter second integer ";
          infile >> n;
          outfile << "The second integer is: " << n << endl;
         
     if (m < n)
     {
          ntemp = n;
          mtemp = m;
          m = ntemp;
          n = mtemp;
     }
     
          r = n % m;
          while(r != 0)
     {
          n = m;
          m = r;
          r = n % m;
     }
     

          outfile << "\nThe GCD is: " << m << endl;
          outfile << "\n";
          outfile << "\n";
}

while(infile >> m) will fail if it reaches the end of file while reading m.  Of course, there's still the possibility that you reach end of file while reading m (if the number of int's in the file is odd), but I'm guessing that won't be a problem.  Good luck.
0
Orlando15767Author Commented:
when I change it to
while (infile >> m)
it skips over the pairs of integers

ex
list of int's ( 9 12 45 62 35 100)
the ones that are read into n and m are 12,45 and 35,100

thanks for the help
0
mnashadkaCommented:
Did you remember to remove the infile >> m in the while loop?
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
C++

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.