Thread: Class Help

You haven't asked a question.

Well... Where should I start? Your code is wrong i'm afraid.

A class defines a blueprint of an object. It is not exactly an Axe. It is instead the plans for a weapon. It describes the properties of that weapon (damage, speed factor, weight, ...) and possibly the actions of that weapon (slash, throw, defend,...). The properties are variables, the actions are functions.

So... to actually create the a very simple weapon class you will do something like this:

Code:

class Weapon {
    public:
        weapon(int damage = 0): dam_(damage) {}
        
        int damage() { return dam_; }
    private:
        int dam_;
}

To better understand the elements above you need to read about classes. Check these links to understand how to work with them:

http://www.cprogramming.com/tutorial/lesson12.html
http://www.cplusplus.com/doc/tutorial/classes.html
http://appsrv.cse.cuhk.edu.hk/~csc45...torial.2/1.htm

char Axe = 20;

you define axe as a char and assign it 20, which is not giving it the value 20 but the ASCII character that 20 represents... axe should be declaired as an int.

cpu;
cpu = 100;

cpu does not name a type, you should have

Code:

int cpu = 100;

there are other errors too, check out the links that Mario posted, they will give you a good starting point for class usage.

cpu = cpu - weapon.Axe

you can also use the -= operator here, like this

Code:

cpu -= weapon.Axe;

I've looked at one of your linked websites and I am having trouble wih understand the code. I have read the explanation like 10 times. But need point explanation, the code in bold is what I dont understand. Code in italic red Im not quite sure but have an idea of what it is. Please let me know if Im correct. If not, dont be afraid to tell me bluntly that Im wrong, which explaining why its different.


class Example_class (name of class)
{ (begins coding)
private: ( makes code limited access to class only)
int x; (parameter of example class)
int y; (parameter of the example class)
public: (dont understand why there are a private and public in the same code)
Example_Class() (constructor)
{ (start block of code)
x = 0; (declare value of x)
y = 0; (declare value of y)
} (end block of code)
~Example_Class() (destructor)
{} (why is there curly brackets with no code)
int Add() ( no clue)
{ (begin block of code)
return x+y; (return the total value of x+y)
} ( end block of code)
}; (ends coding with trailing, semi-colon)

>> please be patient with me

Heh, the worst I can do is ignore ya

Anyways, classes are user-defined types. Think of an int or something. That's a type. So is a char or something, but a class is a type which is defined by the user. This means that it can have anything. One thing that classes possess are member functions, which are functions which belong only within that particular class, and more impartantly, they are relavent to that class -

Here's a very simple example of a class, where there are two variables, and one function which adds the two integers.

Code:

class Add
{
private:
	int x;
	int y;

public:
	Add( void )
	{
		x = 2;
		y = 33;
	}

	int Add_XY ( void )
	{
		return ( x+y );
	}
};

int main( void )
{
	int result;

	Add MyInstance;
	result = MyInstance.Add_XY();

	std::cout<< "The result of Add::Add_XY() is - " << result;

	return 0;
}

Compile this, and see what happens.

I underlined two parts of the code. The part within the class definition defines what happens when you call the function, just like other functions.

Originally Posted by HawkLord

I compiled it and it showed the result of add::add_xy() is -35. just to clarify does the code (void) mean to return?

Nothing. It's void of return.

int funct() - returns an int
char function() - returns a char
etc
void function() - returns nothing

Also:

int funct( void ) - returns an int
char function( void ) - returns a char
etc
void function( void ) - returns nothing

The (void)'s just mean that the functions don't take any parameters. It's strictly not necessary to have them there, but I'm somewhat pedantic about layouts etc.

Do you understand why it returned 35 though?

Here's another example -

Code:

class Add
{
private:
	int x;
	int y;

public:
	Add( int New_x, int New_y ) : x( New_x ), y( New_y )
	// This is called an itilisation list. Just another way of intialising class members
	{
	}

	int Add_XY ( void )
	{
		return ( x+y );
	}
};

int main( void )
{
	int result, User_x, User_y;

	std::cout<< "Enter int one: ";
	std::cin >> User_x;

	std::cout<< "Enter int two: ";
	std::cin >> User_y;

	Add MyInstance( User_x, User_y );
	result = MyInstance.Add_XY();

	std::cout<< "The result of Add::Add_XY() is: " << result;

	return 0;
}

Should you not therefore have void in the constructor, twomey?

Ha, you spellt your quote wrong!

Anyway, what twomers was intensionally showing you was bad programming practice by not sticking to the same syntax for similar coding.