c++ class passing member function issues - c++

Question

In class were learning about classes and structures, Im working on a program that is supposed to have to member functions in the class, one doing calculations and one to return certain values, it seems Im running into trouble calling the functions maybe? IM not a 100% sure because c++ cant specify the error. I hope you can help me, thank you in advance.
#include <iostream>
#include <cstdlib>
using namespace std;
void rocket(double massR,double massE, double massP,double avgTh,double bd);
double rocketreturn(double& MV,double& MA);
class Rocket
{
private:
double massR;
double massE;
double massP;
double avgTh; // average thrust
double bd; //burn duration
public:
void rocket(double massR,double massE, double massP,double avgTh,double bd)
{
massR=massR/1000;
massE=massE/1000;
massP=massP/1000;
double LM=massR+massE;
double MCP=massR+massE-massP;
double AM=(LM+MCP)/2;
double acc=(avgTh/AM)-9.8;
double MV= acc * bd;
double Alt=.5*acc*.5*.5;
double t=MV/9.8;
double MA=Alt+MV*t+.5*-9.8*t*t;
}
double rocketreturn(double& MV, double& MA)
{
cout<< MV;
cout<< MA;
}
};
int main( )
{
double massR; // mass of the rocket
double massE; // mass of the engine
double massP; // mass of the propellant
double avgTh; // average thrust
double bd; // burn duration
double MV; // max velocity
double MA; // max altitude
char ans;
system("CLS");
cout << "Take Home # by - "
<< "Rocket Object\n\n";
do
{
cout <<"Enter the mass of the rocket: "<<endl;
cin >> massR;
cout <<"Enter the mass of the engine: "<<endl;
cin >> massE;
cout <<"Enter the mass of the propellant: "<<endl;
cin >> massP;
cout <<"Enter the average thrust of the engine: "<<endl;
cin >> avgTh;
cout <<"Enter the burn duration of the engine: "<<endl;
cin >> bd;
rocketreturn(MV,MA);
cout <<"the rockets maximum velocity is " << MV<<endl;
cout <<"the rockets maximum altitude is "<<MA<<endl;
cout <<"Would you like to run the program again (Y or N)?"<<endl;
cin>>ans;
}
while(ans=='y'||ans=='Y');
}

Answer 1

You can try using the following program structure and fill in the details the way you wish. Note, it won't compile.
#include <iostream>
using namespace std;
class Rocket {
private:
double mR, mE;
public:
/* Constructor. It is missing in your program. You probably want it */
Rocket(double massR, double massE) {
/* Better to use initialization list, but this should work too */
mR = massR;
mE = massE;
}
double rocketreturn(double & a, double & b) {
/* Do sth with the parameters. But return a double,
which you are not doing in your program */
double result = a + b;
return result;
}
};
int main() {
double x, y;
do {
cin >> x >> y;
Rocket my_rocket(x, y);
double z = my_rocket.rocketreturn(x, y); // Assignment not necessary
} while ( /* some condition */) //my_rocket object will be destroyed after scope goes out
return 0;
}