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Exchange Calculator using classes

Tsirp (1)
I am a beginner in wit c++ and would appreciate some friendly advice. I made a exchange calculator from EUR to a chosen currency and I have to use classes.

If someone could help to improve(and explain it so that also I would understand) my quite hiddeous but compiling code, I would be very grateful.
As said, it compiles but I can't get the 0 == quit working.


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.h file
#pragma once
#include <iostream>
using namespace std;

class Currency {

public:
	//Declaring the variables
	string currencyName;
	double conversionRate;

public:
	//Default Constructor
	Currency();
	//Constructor with two parameters
	Currency(string currencyName, double conversionRate);
	//Destructor
	~Currency();

};
.cpp file
#include <iostream>
#include "MyCurrencyConverter.h"
using namespace std;


Currency::Currency(string pCurrencyName, double pConversionRate)
{
	currencyName = pCurrencyName;
	conversionRate = pConversionRate;

}

Currency::Currency()
{
	currencyName = "";
	conversionRate = 0;
}

Currency::~Currency()
{

}
main.cpp file:
#include <iostream>
#include "MyCurrencyConverter.h"
using namespace std;


int main()
{
    //Initiate all wanted currencies(give value for name parameter and conversion rate parameter)
   

    //create parameters for user input choice=currency & eurAmount for amount of Euros to be exchanged
    int choice;
    double euroAmount;
    //Create Currency "Menu"
    cout << "####################################################################" << endl;
    cout << "##      Choose the Currency;                          ##" << endl;
    cout << "##                                                    ##" << endl;
    cout << "##  1 = Us Dollar                                     ##" << endl;
    cout << "##  2 = Uk Sterling                                   ##" << endl;
    cout << "##  3 = Japanese Yen                                  ##" << endl;
    cout << "##  4 = Australian Dollar                             ##" << endl;
    cout << "##  5 = Canadian Dollar                               ##" << endl;
    cout << "##  6 = Swiss Franc                                   ##" << endl;
    cout << "##  7 = Chinese Renminbi                              ##" << endl;
    cout << "##  0 = Quit                                          ##" << endl;
    cout << "##                                                    ##" << endl;
    cout << "##                                                    ##" << endl;
    cout <<"#########################################################" << endl;

    cin >> choice;//User Input for choosing the currency
    cout << "Give amount of Euros to be exchanged: " << endl;
    cin >> euroAmount;//user input for amount of euros

    //Giving values to objects in class Currency
    Currency usd("US Dollar", 1.10);
    Currency gbp("UK Sterling", 0.84);
    Currency jpy("Japanese Yen", 120.26);
    Currency aud("Australian Dollar", 1.66);
    Currency cad("Canadian Dollar", 1.47);
    Currency chf("Swiss Franc", 1.06);
    Currency rmb("Chinese Yuan", 7.70);



    //The if Loop for calculating the conversion based on user input. Based on choice the function calculates
    //The conversion from EUR  to the  chosen currency.
    if (choice == 1)
    {
         cout << " With " << euroAmount << " Euro, you will get " << euroAmount * usd.conversionRate << " " << usd.currencyName << "." << endl;
    }
    else if (choice == 2)
    {
        cout << " With " << euroAmount << " Euro, you will get " << euroAmount * gbp.conversionRate << " " << gbp.currencyName << "." << endl;
    }
    else if (choice == 3)
    {
        cout << " With " << euroAmount << " Euro, you will get " << euroAmount * jpy.conversionRate << " " << jpy.currencyName << "." << endl;
    }
    else if (choice == 4)
    {
        cout << " With " << euroAmount << " Euro, you will get " << euroAmount * aud.conversionRate << " " << aud.currencyName << "." << endl;
    }

    else if ( choice == 5)
    {
        cout << " With " << euroAmount << " Euro, you will get " << euroAmount * cad.conversionRate << " " << cad.currencyName << "." << endl;
    }
    else if ( choice == 6)
    {
        cout << " With " << euroAmount << " Euro, you will get " << euroAmount * chf.conversionRate << " " << chf.currencyName << "." << endl;
    }
    else if (choice == 7)
    {
        cout << " With " << euroAmount << " Euro, you will get " << euroAmount * rmb.conversionRate << " " << rmb.currencyName << "." << endl;
    }

    else
    {
        cout << "Try again" << endl;
    }
}
nuderobmonkey (640)
Your code looks good at first glance.

I suggest you, adding a method which performs the conversion directly:

 
 
double Currency::convert( double amount ) { return amount * conversionRate; }


A destructor is not needed in your sample class.
Also, I suggest removing the default constructor.
Last edited on
nuderobmonkey (640)
I overworked your program, now it's split into several functions.
The most difficult part is, handling the input in a manner that wrong input will get filtered out.

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#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>

class Currency {

public:
	//Declaring the variables
	std::string currencyName;
	double conversionRate;

public:
	//Constructor with two parameters
	Currency( std::string currencyName, double conversionRate );
	std::string getName() const;
	double convert( double euroAmount ) const;
};


Currency::Currency( std::string pCurrencyName, double pConversionRate)
: currencyName{pCurrencyName}, conversionRate{pConversionRate}
{}

std::string Currency::getName() const { return currencyName; }

double Currency::convert( double euroAmount ) const 
{ 
    // return with two-digit precision for fraction part
    return std::round(euroAmount * conversionRate * 100) / 100.0;
} 


double readCurrencyInput()
{
    std::cout << "Input your Euro amount: ";
    
    while( true )
    {
        std::string line;
        double amount;
        std::getline( std::cin, line );
 
        // stod (string to double) throws an exception if conversion fails
        try {
            amount = std::stod( line );
        } catch (...) {
            std::cout << "You entered a wrong input, try again.\n";
            continue;  // continues the while loop
        }
        
        return amount;
    }
}

int readChoice()
{
    std::cout << "Make your choice: ";
    while( true )
    {
        std::string line;
        int choice;
        std::getline( std::cin, line);
        try {
            choice = std::stoi( line );
        } catch (...) {
            std::cout << "You entered a wrong input, try again.\n";
            continue;
        }
        if( choice >= 0 && choice <= 7 )
            return choice;
        else
            std::cout << "You entered a wrong number, try again.\n";
    }
}
    

void printMenu()
{
    std::cout 
         << "########################################################\n" 
         << "##      Choose the Currency;                          ##\n"
         << "##                                                    ##\n"
         << "##  1 = Us Dollar                                     ##\n"
         << "##  2 = Uk Sterling                                   ##\n"
         << "##  3 = Japanese Yen                                  ##\n"
         << "##  4 = Australian Dollar                             ##\n"
         << "##  5 = Canadian Dollar                               ##\n"
         << "##  6 = Swiss Franc                                   ##\n"
         << "##  7 = Chinese Renminbi                              ##\n"
         << "##  0 = Quit                                          ##\n"
         << "##                                                    ##\n"
         << "##                                                    ##\n"
         << "########################################################\n";  
} 


int main()
{
    using std::cout;

    //Giving values to objects in class Currency
    Currency usd("US Dollar", 1.10);
    Currency gbp("UK Sterling", 0.84);
    Currency jpy("Japanese Yen", 120.26);
    Currency aud("Australian Dollar", 1.66);
    Currency cad("Canadian Dollar", 1.47);
    Currency chf("Swiss Franc", 1.06);
    Currency rmb("Chinese Yuan", 7.70);

    double euroAmount = readCurrencyInput();
    
    // setting the ouput format
    cout << std::fixed << std::setprecision(2);
    
    while( true )
    {
        printMenu();
        int choice = readChoice();
        if( choice == 0 ) {
            std::cout << "Bye!\n";
            return 0;
        }
        
        cout << "With " << euroAmount << " Euro, you will get ";
        switch( choice )
        {
            case 1: cout << usd.convert( euroAmount ) << " " << usd.getName(); break;
            case 2: cout << gbp.convert( euroAmount ) << " " << gbp.getName(); break;
            case 3: cout << jpy.convert( euroAmount ) << " " << jpy.getName(); break;
            case 4: cout << aud.convert( euroAmount ) << " " << aud.getName(); break;
            case 5: cout << cad.convert( euroAmount ) << " " << cad.getName(); break;
            case 6: cout << chf.convert( euroAmount ) << " " << chf.getName(); break;
            case 7: cout << rmb.convert( euroAmount ) << " " << rmb.getName(); break;
        }
        cout << '\n';
    }    
}
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