Question

I’m trying to write a program that will save the contents of a linked list (each individual list is called a locality and includes a mix of data types). The code compiles but terminates unexpectedly; it refers me to the lines in the ifstream library (even though I only want to be using writing)

*_Str = _Elem();    // add terminating null character

Does anyone have an idea whats gone wrong?

   //saves a single locality onto a file
    void fSave_locality(Clinked *current, fstream *fout)
    {
        fout->write(current->site_name,100);
        fout->write((char*) &current->cood_x,sizeof(double));
        fout->write((char*) &current->cood_y,sizeof(double)); 
        fout->write((char *) &current->dip,sizeof(double)); 
        fout->write((char *) &current->strike,sizeof(double)); 

        if (current->next!=NULL) fSave_locality(current->next,fout);
    }

    void fSave_list(char* fname)
    {
        fstream *fout;
        do
        {
            cout<<"Would you like to save as a (b)inary or (t)ext file? ";
            test = getch();
            cout<<"Enter file name (make sure its unique!): ";
            cin.getline(fname,100);

            if(toupper(test)=='T') fout->open(fname, fstream::out);
            if(toupper(test)=='B') fout->open(fname, fstream::out| fstream::binary);
        }
        while(toupper(test)!='T' || toupper(test)!='B');

        if(fout->fail())
        {
            cout<<"unable to open file.\n";
            exit(0);
        } //it gets to here without any problems. 

        current = start;
        while(current->next!=NULL)
            {
                fSave_locality(current, fout);
                current=current->next; //repeat for the next object in the list
            }
        fout->close();
    }

Answer 1

I don’t understand why you are iterating recursively and sequentially in the same time ?
Just choose one or the other, I changed the code, you also need to set a correct limit to your while loop and make sure you do not use a null object and try to access elements on a null object.

  void fSave_locality(Clinked *current, fstream *fout)
    {
        fout->write(current->site_name,100);
        fout->write((char*) &current->cood_x,sizeof(double));
        fout->write((char*) &current->cood_y,sizeof(double)); 
        fout->write((char *) &current->dip,sizeof(double)); 
        fout->write((char *) &current->strike,sizeof(double)); 

        //if (current->next!=NULL) fSave_locality(current->next,fout); // comment this out
    }

and change the below part :

while(current!=NULL)
    {
        fSave_locality(current, fout);  // you should either comment this one or the recursive one
        current=current->next; //repeat for the next object in the list
    }