Negative pressure Unit Calculator (revised)

gistfile1.cpp

/**
 * Calculate the amount of Negative pressure needed for a given size of an enclosed area.
 * @authr Phoenix560.
 * November 2012
 */

#include <iostream>
#include <cmath>

using namespace std;

bool sanitiseIO( istream& stream ) {
    bool badStream = false;
    if ( stream.fail() ) badStream = true, cin.ignore(1000,'\n');
    cin.clear();
    return badStream;
}

template <typename type>
type getValueIfGreaterThanZero( istream& in , ostream& out ) {
    type result;
    while (true) {
        in >> result;
        sanitiseIO(cin);
        
        if( result > 0 ) break;
        else
            out << "must have a value higher than 0! " << endl;
    }
    return result;
}

int main()
{
    // variables for the option of Units
    char units;
    
    // Start with unit conversion from cubic metres to cubic feet.
    
    // Variables for Length, Width and height.
    float length, width, height;
    
    // Variables for cubic metres, cubic feet and air changes
    float cubicfeet, cubicmetres, answer;
    int airchanges;
    
    //request user input for Measurement Units
    cout << "Please enter units ('F' for Feet OR 'M' for Metres): " << flush;
    
    for(bool success = false; !success; )
    {
        cin >> units;
        sanitiseIO(cin);

        // I FRIGGIN MISS RUBY BLOCKS RIGHT HERE... *"'>_<'"*
        // I can't make it smaller without making it bigger somewhere else and more
        // mindfucking... That's the C++ paradox...
        
        switch (units) {
            case 'M':
            case 'F':
                success = true;
                break;
                
            default:
                cout << "Must be either feet ('F') Or Metres ('M')" << endl;
                break;
        }
    }
    
    // deturmine the length of the area in metres and validate user input
    cout << "Please enter the Length of the area: " << flush;
    length = getValueIfGreaterThanZero<float>(cin,cout);
    
    // deturmine the height of the area in metres and validate user input
    cout << "Please enter the Width of the area: " << flush;
    width = getValueIfGreaterThanZero<float>(cin,cout);

    // deturmine the height of the area in metres and validate user input
    cout << "Please enter the Height of the area: " << flush;
    height = getValueIfGreaterThanZero<float>(cin,cout);
    
    //determine amount of air changes and validate user input
    cout << "Please enter the required amount of air changes (Minimum of 8): " << flush;
    airchanges = getValueIfGreaterThanZero<int>(cin,cout);
    
    //Run calculation
    if(units == 'F') {
        cubicfeet = ((length * width) * height);
        answer = (cubicfeet * airchanges) / 60;
        cout << "\nThe result is (answer) " << (double)answer << "cfm" << endl << endl;
    }
    else if(units == 'M') {
        cubicmetres = (length * width) * height;
        cubicfeet = cubicmetres * 3.2808399;
        answer = (cubicfeet * airchanges) / 60;
        cout << "\nThe result is " << (double)answer << "cfm" << endl << endl;
    }
    else {
        cout << "error" << endl;
    }
    
    // Sugest NPU sizes:
    // (Try to fugure out a more generic way to do this)
    // (as in, try to use formula or what not, and substutute placeholders in the answer)
    // (I'd take a stab at this, but I have no bloody clue what this thing is doing)
    if(answer <= 500)
        cout << "You need a 500cfm Negative Perssure unit! " << endl;
    else if ((answer > 500) && (answer <= 850))
        cout << "You need 1 x 850 Or 2 x 500cfm Or, 1x 1500cfm! " << endl;
    else if ((answer > 850) && (answer <= 1000))
        cout << "You need 2 x 500cfm Or, 1x 1500cfm! " << endl;
    else if ((answer > 1000) && (answer <= 1500))
        cout << "You need a 1500cfm Negative pressure unit! " << endl;
    else if ((answer > 1500) && (answer <= 2000))
        cout << "You need 1 x 1500cfm and 1 x 500cfm OR," << endl,
        cout << "1 x 2000cfm Negative pressure unit! " << endl;
    else if ((answer > 2000) && (answer <= 3000))
        cout << "You need 2 x 1500cfm Negative pressure units! " << endl;
    else if ((answer > 3000) && (answer <= 4000))
        cout << "You need 2 x 2000cfm OR, 1 x 4000cfm Negative pressure unit!" << endl;
    else if ((answer > 4000) && (answer <= 4500))
        cout << "You need 1 x 4000cfm and 1 x 500cfm Negative pressure units! " << endl;
    else if ((answer > 4500) && (answer <= 5500))
        cout << "You need 1 x 4000cfm and 1 x 1500cfm Negative pressure units! " << endl;
    else if ((answer > 5500) && (answer <= 6000))
        cout << "You need 1 x 4000cfm and 1 x 2000cfm Negative pressure units! " << endl;
    else if ((answer > 6000) && (answer <= 8000))
        cout << "You need 2 x 4000cfm Negative pressure units! " << endl;
    else
        cout << "Answer unknown, error?\n\n";
    
    return 0;
    
}