I need help with getting my lunar class to work in C++

[joder2006]

So I'm working on this class and I have a major problem.

This class happens to be for a rocket, it's a game that you play and you try to see it you can land safely from 1000 meters up in the air.

The problem is when I input the throttle the program ignores it.

It doesn't matter what i input into the throttle i get the same result.

There are also other problems as well.

Some of my accessors don't change correctly.

What is wrong with my program?

Here is my code first i have the cpp.

I don't know if this helps but im running this off of a Win XP PC using Visual studio 2005.

 -------------------------------------------------------------------------------------------------------------- 
 
[
 
// Program6.cpp
// Elliot Weimann
// November 21, 2006
// This program is a rocket game
// Computer Science 210
 
#include <iostream>
#include <string>
#include "program6.h"
 
using namespace std;
 
void changetime();
 
void main()
{
    int throttle = 0;
    int time = 0;
 
 
    lunar c1;
    c1.setFuelflow(0.0);
 
cout << "Welcome to my rocket game try to land the rocket safetly from 1000 meters" << endl;
cout << "To start input the time interval" << endl;
cin >> time;
 
while (c1.getAltitude() > 0 && c1.getAltitude() != 0)
 
{
 
 
 
    cout << "Enter a number 1 through 10 for the fuel flow rate " << endl;
    cin >> throttle;
    cout << "Your altitude is " << c1.getAltitude() << endl;
    cout << "Your mass is " << c1.getMass() << endl;
    cout << "Your fuel is " << c1.getFuel() << endl;
    cout << "Your speed is " << c1.getVerticalspeed() << endl;
 
    if ( throttle > 10 || throttle < 0)
    {
        cerr << "You can't input that amount" << endl;
        system("pause");
        return;
    }
 
 
 
c1.setFuelflow(throttle/10.0);
 
 
 
         for (int i = 0; i < time; ++i)
         {
            c1.setPasstime(.01);
 
         }
 
 
}
 
{
if (0 > c1.getVerticalspeed() && c1.getVerticalspeed() > -10 || c1.getVerticalspeed() == 0)
 
    cout << "safe landing" << endl;
 
 
else
 
    cout << "unsafe landing" << endl;
 
} 
system("pause");
}
 
--------------------------------------------------------------------------------------------------
Here is my implentation file
--------------------------------------------------------------------------------------------------
// Program6implentation.cpp
// Elliot Weimann
// November 21, 2006
// This program is a rocket game
// Computer Science 210
 
#include <iostream>
#include "program6.h"
 
using namespace std;
 
lunar::lunar()
{
    thrust = 5000;
    altitude = 1000;
    mass = 900;
    fuel = 1700;
    fuelrate = 10;
    fuelflow = 0;
    verticalspeed = 0;
    passtime = .01;
}
 
float lunar::getFuel()
{
    fuel += passtime * fuelrate * fuelflow;
    return fuel;
}
 
float lunar::getFuelrate()
{
    return fuelrate;
}
 
float lunar::getThrust()
{
    return thrust;
}
 
void lunar::setFuelflow(float)
{    if (fuel == 0 && fuelflow > 0)
{
fuelflow = 0;
}
}
 
float lunar::getFuelflow()
{ 
    return fuelflow;
}
 
float lunar::getMass()
{
    mass = mass + fuel;
    return mass;
}
 
 
 
void lunar::setPasstime(float)
{passtime += .01;
 
}
 
float lunar::getPasstime()
{    
     return passtime;
}
 
float lunar::getAltitude()
{
    altitude += passtime * verticalspeed;
 
if(altitude < 0)
{
    altitude = 0;
}
 
if(altitude > 1000)
{
    altitude -= passtime * verticalspeed;
}
return altitude;
}
 
void lunar::setVerticalspeed(float)
{
 
}
 
float lunar::getVerticalspeed()
{
 
verticalspeed += passtime * ((thrust * fuelflow)/mass) - 1.62;
     return verticalspeed;
 
}
---------------------------------------------------------------------------------------------------
here is my header file
--------------------------------------------------------------------------------------------
// Program6.h
// Elliot Weimann
// November 21, 2006 
// This program is a rocket game 
// Computer Science 210
 
#ifndef LUNAR_H
#define LUNAR_H
 
class lunar 
{
public:
 
    lunar();
    lunar(float, float);
 
    // Set time of lunar
    void setPasstime(float);
 
 
    // Set fuel of lunar
    void setFuelflow(float);
 
    // Set speed of lunar
void setVerticalspeed(float);
 
    // get thrust of lunar
    float getThrust();
 
    // get time of lunar
    float getPasstime();
 
// get altitude of lunar
    float getAltitude();
 
    // get mass of lunar
    float getMass();
 
    // get fuel of lunar
    float getFuel();
 
    // get fuel of lunar
    float getFuelrate();
 
    // get fuel of lunar
    float getFuelflow();
 
    // get fuel of lunar
    float getVerticalspeed();
 
float fuelflow;
 
private:
    // Data members (attributes)
    float fuel;
float altitude;
    float mass;
    float thrust;
    float fuelrate;
    float verticalspeed;
    float passtime;
};
#endif // LUNAR_H
 
 
]
 
 
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[DeMan]

Have you tried outputting the throttle value that you pass in to make sure that the value is what you intend?

[joder2006]

yes i just did that and it couts what i input, the thing is though when i output the fuelflow it says its always zero no matter what i input, and zero is what it starts out at.

[DeMan]

fuelflow is defined as a float, yet is used in various places as though it were an int. This in itself is not a problem in so far as the program is usually happy to cast it, but when things get unintentionally cast, interesting things can happen.. When casting a number from a float to an int, for example, you get a rounding effect identical to calling a 'floor' function. It always pays to be pedantic and use 0.0 rather than 0 for floats (although I just spotted something else)

Also your set fuelfuel flow method is a little odd

void lunar::setFuelflow(float)
{    
if (fuel == 0 && fuelflow > 0)
 {
  fuelflow = 0;
 }
}
 

As far as I can tell, this method only set's the fuelflow if fuel==0 and fuelflow>0 (in which case it set's it to 0). Firstly I think the second test is redundant (in that you wouldn't really care whether fuel is flowing or not, if the tank is 0 then stop fuelflow). More importantly you should do something with your input. I think you nmay have meant something like:

void lunar::setFlow(float new_flow)
{
  if(fuel==0 && fuelflow>0) //I have left it your way assuming there is a reason
  {
    fuelflow=0;
  }
  else
  {
    fuelflow=new_flow;
  }
}
 

[joder2006]

thanks i did what you said and it seems to work now.