Question

I have built GMP for MinGW. The IDE I’m using is Code::Blocks. I don’t have any problems with C functions of GMP. But I’m having problem with C++. The program I tried to run is as simple as this,

#include<iostream>
#include<gmpxx.h>
using namespace std;

main()
{
    mpz_class a;
    a=12345;
    cout<<"value"<<a<<"\n";
    return 0;
}

And the Errors I get are

F:\Compilers\C_Libraries\GMP\lib\libgmpxx.a(osmpz.o):osmpz.cc|| undefined reference to `__gmpz_get_str'|
F:\Compilers\C_Libraries\GMP\lib\libgmpxx.a(osfuns.o):osfuns.cc:(.rdata+0x1c)||undefined reference to `__gmp_asprintf_memory'|
F:\Compilers\C_Libraries\GMP\lib\libgmpxx.a(osfuns.o):osfuns.cc:(.rdata+0x20)||undefined reference to `__gmp_asprintf_reps'|
F:\Compilers\C_Libraries\GMP\lib\libgmpxx.a(osdoprnti.o):osdoprnti.cc|| undefined reference to `__gmp_doprnt_integer'|
F:\Compilers\C_Libraries\GMP\lib\libgmpxx.a(osdoprnti.o):osdoprnti.cc|| undefined reference to `__gmp_asprintf_final'|
||=== Build finished: 5 errors, 0 warnings ===|

Now, some additional data:

1. I don’t have any problem with C functions. And also, if I remove cout<< statement the file compiles and runs fine. The problem is probably with overloaded operators.
2. libgmpxx.a and libgmp.a are linked with compiler. It can be seen in the error messages too…
3. The problem is probably with the libgmpxx.a alone. So, I built the Library again, but the files are same.
4. I used this tutorial build GMP with MSYS for MinGW. http://www.cs.nyu.edu/exact/core/gmp/ and http://suchideas.com/journal/2007/07/installing-gmp-on-windows/
5. The version of GMP I’m using is 5.0.4.

So, what I want to know is, what could be the problem? And how could it be solved?
And, if unsolvable and if you have the working files for 5.0.4 version, please share it. 🙁

Answer 1

I suspect the command to build your program specifies the libgmp* libraries in the wrong order. Make sure the libgmp.a library is specified after the libgmpxx.a library:

-lgmpxx -lgmp

If they are specified in the other order, then when pulling in dependencies from libgmpxx.a library, the libgmp.a library won’t be searched.

From the ld linker’s docs on the -l option:

The linker will search an archive only once, at the location where it
is specified on the command line. If the archive defines a symbol
which was undefined in some object which appeared before the archive
on the command line, the linker will include the appropriate file(s)
from the archive. However, an undefined symbol in an object appearing
later on the command line will not cause the linker to search the
archive again.

See the -( option for a way to force the linker to search archives
multiple times.

You may list the same archive multiple times on the command line.