Can help to check if I coded correctly?

[prtyrckk]

Hello Everyone,

For my assignment, I am required to apply three constructors for the WeeklySales class:

- a parameterised constructor with the encessary paramaters to initialise all the data members of a WeeklySales instance.

- a default constructor that will initialise the data members salesPerson to "Unknown", noOfWeek to 13 and amount to point to an array of thirteen "0.00".

- a copy constructor that will create a new WeeklySales instance and copy the values of the data members from an existing WeeklySales instance to the new WeeklySales instance

The code below works fine just that I am seeking opinion if I am doing it correctly?

#include <iostream>
using namespace std;

class WeeklySales
{
	char* salesPerson;
	double* amount; // Pointer to an array
	int noOfWeek; // Size of the array
public:

	// parameterised constructor
	WeeklySales(char* personSales, double* amountToArray, int arraySize)
	{
		salesPerson = new char[strlen(personSales) + 1];
		strcpy(salesPerson, personSales);
		amount = amountToArray;
		noOfWeek = arraySize;
	}

	// default constructor
	WeeklySales()
	{
		salesPerson = new char[strlen("Unknown") + 1];
		strcpy(salesPerson, "Unknown");
		//amount = 0.00;
		noOfWeek = 13;
		double amtArray[] = {0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.00};
		amount = amtArray;
	}

	// Copy constructor
        //& <-- reference/pointing || Cloning/copy
	WeeklySales(const WeeklySales& weeklySalesCopy)  
	{
		salesPerson = new char[strlen(weeklySalesCopy.salesPerson) + 1];
		strcpy(salesPerson, weeklySalesCopy.salesPerson);
		amount = weeklySalesCopy.amount;
		noOfWeek = weeklySalesCopy.noOfWeek;
	}
 

	//print for test purpose
	void printweeklySalesCopy()
     {
		 cout << "Name of Salesperson: " << salesPerson << endl;
		 cout << "Amount: $" << amount << endl;
		 cout << "Number of Weeks: " << noOfWeek << endl << endl;
     }
};

 

int main ()
{
	// parameterised
	WeeklySales test1;
	cout << "Account 1 using parameterised constructor\n";
	test1.printweeklySalesCopy();

	// default
	WeeklySales test2;
	cout << "Account 2 using default constructor\n";
	test2.printweeklySalesCopy();

	// copy
	WeeklySales test3(test2); //cloning
	cout << "Account 3 via cloning through copy constructor\n";
	test3.printweeklySalesCopy();
}

[prtyrckk]

Sorry. I just realised that when the output for amount comes out some random hex value. What could be the cause of it?

Any help is truly appreciated.

[keskiverto]

The 'amount' is a pointer. The closest operator<< is the one that takes a pointer and shows the stored address, not the operator that takes a double. You have to dereference the pointer to get the intended value out.

The amtArray is a local variable, which expires on line 29. Thus, the 'amount' holds an address to invalid memory location after the constructor call is complete.

[prtyrckk]

thanks for replying, keskiverto.

sorry i am still quite new to c++ therefore i do not quite understand what u are saying..

[Mats]

Instead of explaining these errors for this case, it's best if you learn the general theory.

Here is pointers: http://www.cplusplus.com/doc/tutorial/pointers/

I couldn't find a decent tutorial on scope online (I guess you need to read a C++ book). Here is a quick explanation.

void somefunction()
{
    int x; //This variable is now accessible to this function. 
    x = y; //This will not work, because y is out of scope. 
}

int main()
{
    int y; //This variable is in scope of main(). 
    x = 5; //This will not work, because x is out of scope. 
    return 0;
}

To move values between functions, you can do this:

 
void somefunction(int) //We say that somefunction takes an argument of an integer called z. 
{
    int x; 
    x = z; //z is now in scope, because it was passed from main() to this function.  
}

int main()
{
    int y = 5; //This variable is in scope of main() and only accessible to main().
    somefunction(y); //but we can pass the value to the function as an argument. 
    return 0; 
}