• C

Displaying Long Double

I've declared a long double variable and tried to display it but could only display in exponential format.

The problem is, C allows me to declare a long double but printf and sprintf only handles up to the size of double (16 digits).

I need to at display the full value on the screen as well as converting it to a string using sprintf. To illustrate:

/* Dummy codes */
long double buf1, buf2, result;
char ans[20];

buf1 = 12345678901234567.00;
buf2 = 12345678901234567.00;
result = buf1+buf2;
printf("result: %17.0f", result);
sprintf(ans, "%17.0f", result);

If printf and sprintf can't work please suggest other alternatives.

Note: The maximum length of the variable "result" can go up to 18 digits.

Please help, this is urgent. Thank you.
samtanAsked:
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.

warren_daleCommented:
(1) Long double is not ANSI C. It is an extension.
(2) On my machine I can only get 17 significant figues for long double. You may be asking for more than is available.
(3) Are you only using whole numbers? If so:
(3.1) consider looking at one of the multiple-precision-integer packages that are around.
(3.2) consider using "long long integer" which gcc (at least) supports.
Both of these enable you to use 64 bit integers, which give up to 20 decimal digits. (If you are on a Digital Alpha they are native).
0
AVaulinCommented:
Try to use "fcvt" function. Prototype is in "stdlib.h".
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
prcCommented:
No, fcvt takes a double argument.

You can use (s)printf in some systems.  It's not part of the ANSI spec for (s)printf though.  In GNU library systems (including Linux), you can use the 'L' prefix (yes, upper case).  In BSD, you can use 'q'.  Actually, you can use 'q' in both, so that's the more portable (but not Portable) way of doing it.

The follow code works fine on Linux:

#include <stdio.h>

int main()
{
  long double a,b,c;
  a=12345678901234567.00;
  b=12345678901234567.00;
  c=a+b;
  printf("result: %17.0qf\n", c);  /* Or Lf */
  return 0;
}

If this is any good to you, reject the above and I'll enter an empty answer for you to accept.

Cheers

Paul
0
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.