Error " undefined reference to `std::ios_base" while linking cpp header only library to fortran

Question

I am trying to link a header only library (which is in cpp) to a fortran code. I am using this example to test my library.

   $ cat cppfunction.C
   #include<cmath>
   #include<mylib/mylib.hpp>

   extern "C" 
   {
        void cppfunction_(float *a, float *b);
   }
   void cppfunction_(float *a, float *b)
   {
        *a=7.0;
        *b=9.0;
   }

  $ cat fprogram.f

   program fprogram

   real a,b
   a=1.0
   b=2.0

   print*,"Before fortran function is called"
   print*,'a=',a
   print*,'b=',b

   call cppfunction(a,b)
   print*,"After cpp function is called"
   print*,'a=',a
   print*,'b=',b

   stop
   end

For compiling I am using:

    $ gfortran -c fprogram.f
    $ g++ -c cppfunction.C
    $ gfortran -lc -o fprogram fprogram.o cppfunction.o

This runs fine if I remove my library header. But have this error when included:

    cppfunction.o: In function `__static_initialization_and_destruction_0(int, int)':
    cppfunction.C:(.text+0xa1): undefined reference to `std::ios_base::Init::Init()'
    cppfunction.C:(.text+0xb0): undefined reference to `std::ios_base::Init::~Init()'
    collect2: error: ld returned 1 exit status

Anything I might be doing wrong?

What is the content of `mylib.hpp`? You are probably including `iostream` or similar. — rveerd, Jan 06 '20 at 12:37
It seems the linker is linking with libc instead of libstdc++, in other words you need to link in C++ mode somehow. — rustyx, Jan 06 '20 at 12:41
@rveerd Yes. mylib contains function similar to std::cout to print variables. — Ashish Magar, Jan 06 '20 at 12:43
It should be noted that the order of `-l` and object files in the command line **does** matter. — Evg, Jan 06 '20 at 12:55

score 0 · Accepted Answer · answered Jan 06 '20 at 12:43

0

You're not linking the C++ standard library:

gfortran -lc -lstdc++ -o fprogram fprogram.o cppfunction.o
//           ^^^^^^^^

answered Jan 06 '20 at 12:43

Lightness Races in Orbit

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Thanks. I was using this while compiling the .C file with g++. – Ashish Magar Jan 06 '20 at 12:49
@Evg Yes. I was using -lstdc++ while compiling with g++. The complete command in above answer helped. – Ashish Magar Jan 06 '20 at 12:55
1

`-lstdc++` should come **after** object files (at least, after C++ one), not before them. Otherwise, "undefined reference" is issued. – Evg Jan 06 '20 at 12:58
@AshishMagar Your `g++` invocation has `-c` (compile-only) so does not involve any libraries. – Lightness Races in Orbit Jan 06 '20 at 12:58

Error " undefined reference to `std::ios_base" while linking cpp header only library to fortran

1 Answers1