问题

我正在尝试将一个仅包含头文件的C++库与Fortran代码连接起来。我正在使用此示例来测试我的库。

$ 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

编译时我使用了以下命令：

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

如果我移除我的库头文件，这个编译是正常的。但是当我包括它时，会出现以下错误：

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

我可能做错了什么吗？

<details>
<summary>英文:</summary>

I am trying to link a header only library (which is in cpp) to a fortran code. I am using [this example][1] to test my library.


       $ cat cppfunction.C
       #include&lt;cmath&gt;
       #include&lt;mylib/mylib.hpp&gt;

       extern &quot;C&quot; 
       {
        	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*,&quot;Before fortran function is called&quot;
       print*,&#39;a=&#39;,a
       print*,&#39;b=&#39;,b

       call cppfunction(a,b)
       print*,&quot;After cpp function is called&quot;
       print*,&#39;a=&#39;,a
       print*,&#39;b=&#39;,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)&#39;:
        cppfunction.C:(.text+0xa1): undefined reference to `std::ios_base::Init::Init()&#39;
        cppfunction.C:(.text+0xb0): undefined reference to `std::ios_base::Init::~Init()&#39;
        collect2: error: ld returned 1 exit status


Anything I might be doing wrong?

  [1]: https://www.cae.tntech.edu/help/programming/mixed_languages

</details>


# 答案1
**得分**: 0

你没有链接C++标准库：

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

<details>
<summary>英文:</summary>

You&#39;re not linking the C++ standard library:

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

</details>