在C ++中绑定C函数（未定义的引用）

Question

I have a regular C++ class like PardisoSolver.h:

#ifndef PARDISOSOLVER_H_
#define PARDISOSOLVER_H_

class PardisoSolver {
public:
    /* Initializes a new Solver with the given matrix in CSR */
    PardisoSolver(
            int* ia,
            int* ja,
            double* a,
            int n,
            int nja);
    virtual ~PardisoSolver();
    void setMatrixType(int mtype);
    void pardisoSymFactorize();

private:
    static int get_nproc(void);
    void handle_error(int ierror, int line);

    int* ia;        // row indices
    int* ja;        // column pointer
    double* a;      // non zero values
    int n_eq;       // size of matrix
    int nja;        // number of non zero elements

    bool factorized;

    /* PARDISO SETTINGS */
    void *pt[64];
    int maxfct;
    int mnum;
    int mtype;
    int perm;
    int nrhs;
    int iparm[64];
    int msglvl;
    int error;
    double   dparm[64];

    double dzero;
    int izero;

};

#endif /* PARDISOSOLVER_H_ */

And on the other hand I have the implementations in PardisoSolver.cpp. Here I have an additional declaration of a C function just along with the implementations of the class:

extern "C" void pardiso     (void   *, int    *,   int *, int *,    int *, int *,
              double *, int    *,    int *, int *,   int *, int *,
                 int *, double *, double *, int *, double *);

Now when I try to call that function like

pardiso (pt, &maxfct, &mnum, &mtype, &phase,
       &n_eq, a, ia, ja, &izero, &nrhs,
       iparm, &msglvl, &dzero, &dzero, &error,  dparm);

I get the compile error

PardisoSolver.cpp:94: undefined reference to `pardiso'

where the call is in line 94. Did I declare the C function in the wrong place? As I got it, it cannot be a member of a class so this should be the way to call it. Thanks for the help.

Answer 1

All of this suggest that your program design needs improvment. First of all, there should only be one interface to your "module" (class + other stuff). You should not have "a class, and then some", that doesn't make any sense. All functions related to the functionality of the class should be included in that class. All that aren't related, should be moved to another part of the program.

Once you have straightened that out, you need to clarify the programming language. Is this C or C++? Is it C++ with a caller in C? It seems to be the latter. If so, you need to separate the two languages somehow. As one example: in Windows you could place the C++ class in a DLL, with an interface that can be called from C.

And finally, you should consider whether it makes sense to have a function taking 17 pointers as parameters. Are these parameters not related at all? Could they be grouped in structs/classes? Or perhaps this is simply a needlessly complex monster function, that could be split in several different ones.