The problem with the write integer part of mpf_t really big numbers to the file

lswierczewski . luk.swierczewski at
Sun Aug 24 22:35:19 UTC 2014


I have a problem with GMP.

I don't know how to save to file a floating-point number (mpf_t). I know
that I can use function:


This method have two important restrictions:

1. Scientific notation (I need to use additional conversion)
2. Saved value have restricted precision (as I remember there is above 2000

As the first point isn't really a problem for me that second disqualify
this method for various reasons. I'm working on really big numbers (up to
even 10^(100 000 000 000)) and I need save only integer part of total value.

There can be used:

   gmp_fprintf(fp, "%.0Ff", result);

but this function doesn't save correctly values above (about) 10^(50 000
000) - in my case saves only zero (0). Even if this is a bug in my version
of GMP this function will not be usefully because it can save only 2^31-1
characters (it sends back int type - 4 bytes of number of saved characters)
This gives me maximal value which can be saved equals 2 147 483 647 digits
- which value is far to low and unaccepted for me.

At the moment I have solved problem by using:

   gmp_printf("%.0Ff", result);

and start my "program" by using:

   ./program > output.txt

But function gmp_printf() also have limit for displayed characters
(probably it is also 2^31-1 characters - It doesn't display more characters
for me and displays only zero (0) for bigger values).

I don't know if this is right group to ask how go around my problem.

If is no any simple method I would like do ask for adding new function to
save really big floating-point numbers (mpf_t). In this scenario I need to
save integer part of floating-point precision number.

Best Regards
Lukasz Swierczewski

Tel: (+48) 664 297 198
Email: luk.swierczewski at

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