OOP help

[Windwhistles]

Hello,
I made this program simply for practice using classes.

main.cpp

/*this program:
-finds the distance between 2 points
*/




#include <iostream>
#include <cmath>
#include "Declarations.cpp"




using namespace std;




int main()
{
    Distance coordinates;   //holds coordinates
    double x1, x2;  //x coordinates
    double y1, y2;  //y coordinates

    //get coordinates from the user
    cout<<"Enter the first X coordinate.  ";
    cin>>x1;

    cout<<"Enter the first y coordinate.  ";
    cin>>y1;

    cout<<"Enter the second x coordinate.  ";
    cin>>x2;

    cout<<"Enter the second y coordinate.  ";
    cin>>y2;

    //set the coordinates
    set(x1, x2, y1, y2);

    //print the distance
    cout<<"\n\nThe distance is "<<get_dist()<<endl;

    //pause the program
    cin.get();

    //terminate the program
    return 0;
}




//----------------------------------------------------------------------------------------------------------------------
//Distance class functions

void Distance::set(double a1, double a2, double b1, double b2)    //sets the x and y coordinates
{
    a1=x1;
    a2=x2;
    b1=y1;
    b2=y2;

    //calculate the distance
    dist=calc();
}




double Distance::calc()   //calculates the distance between 2 points
{
    return (sqrt( (x2-x1)*(x2-x1) - (y2-y1)*(y2-y1) ));
}

//-------------------------------------------------------------------------------------------------------------------------- 

Declarations.cpp

//finds the distance between 2 points
class Distance
{
    private:
        double x1, x2;  //x coordinates
        double y1, y2;  //y coordinates
        double dist;    //holds the distance between 2 points
    public:
        void set(double a1, double a2, double b1, double b2);   //sets x and y values
        double get_dist()
            {return dist;}
    private:
        double calc();  //calculates the distance between 2 points
}

There is an error in main.cpp on line 15. Error: expected unqualified-id before 'using'. I have been trying to solve this problem for some time now, and I can't get it. Thanks for your help.

[TightCoder]

Line 14 in Declarations.cpp needs ";"

[zb0S216C]

You should not include source files; only header files. Also, you're missing a semi-colon after the closing brace of the Distance class.

_Wazzak

[Lowest0ne]

To solve your problem, put a semi-colon at the end of line 14 in Declarations.cpp

However, you shouldn't be #include-ing .cpp files.

Make a new file "Declarations.h" and cut/paste the lines from Declarations.cpp to it. Then cut/paste the Distance class functions from main.cpp into Declarations.cpp. Put #include Declarations.h" at the top of Declarations.cpp and main.cpp.

Example:

main.cpp

#include "example.h"

int main(){
  Example example;
  example.write();
  cin.get();
  return 0;
}

example.h

class Example{
public: 
  Example(){};
  ~Example(){};
  
  void write();
};

example.cpp

#include <iostream>
#include "example.h"

void Example::write()
{
  std::cout << "Hello World\n";
}

[Windwhistles]

Thanks everyone for all your help. LowestOne, if I replace Declarations.cpp with Declarations .h, could I get rid of Declarations.cpp altogether?

[Lowest0ne]

Something like this?

Example:

main.cpp

#include "example.h"

int main(){
  Example example;
  example.write();
  cin.get();
  return 0;
}

example.h

#include <iostream>

class Example{
public: 
  Example(){};
  ~Example(){};
  
  void write();
};

void Example::write()
{
  std::cout << "Hello World\n";
}

Yes, this works. I'm not sure of the reasoning behind having that extra .cpp, but I imagine it is a good one :)