Help with Class'

[AaronHod]

char nodeLocation = 'A';

do {     
    Node * foo = new Node(nodeLocation);
    cout << "You are currently in room: \"" << foo->getName() << "\"" << endl;
    cout << "Please enter a direction: "; cin >> nodeLocation;
    }
    
while(nodeLocation != 'L');

    cout << "You have reached the end of the Maze!" << endl;
    cout << "Congratulations!" << endl;
    system("PAUSE");

Basically my "Maze" has 12 nodes, from A-L. Each node has a set of directions it can travel in... For example, "A" can go East or South... How can I make this possible? I can't think of anyway... I want to use something like "foo->getDirections()" to say which directions are possible... I can probably figure the rest out...

[GCDEF]

I'd probably set up bool functions such as CanMoveNorth() that would return true or false.

[AaronHod]

Must be a simpler way than that?

[AaronHod]

So:

1) Start at "A"
2) Give available directions (HOW??!!)
3) Choose a direction
4) Set location to new node location (eg if "East" is selected, set nodeLocation to "B"

[Paul McKenzie]

Basically my "Maze" has 12 nodes, from A-L. Each node has a set of directions it can travel in... For example, "A" can go East or South... How can I make this possible?

Create 4 const ints that represent north, south, east, and west. Number these ints, 1, 2, 4, and 8.

Then create a Node class that has a private unsigned int that holds the boolean OR of these values, denoting the possible directions.

const int NORTH = 1;
const int EAST = 2;
const int WEST = 4;
const int SOUTH = 8;

class Node
{
      unsigned int possibleDirections;
    public:      

          Node(unsigned d) : possibleDirections(d) { }
          unsigned int getDirections( ) const { return possibleDirections; }
};

int main()
{
   unsigned myDirections = NORTH | SOUTH;
   Node node1( myDirections );  // Node only goes north and south

   unsigned curDirections = node1.getDirections( );
   // how do you "parse" the directions out of the returned int?
}

I leave it to you to determine how to find the possible directions given the integer that is returned to you.

Regards,

Paul McKenzie

[GCDEF]

I leave it to you to determine how to find the possible directions given the integer that is returned to you.

Regards,

Paul McKenzie

That's another way to do it, but there's still no way around an if statement determining which of the four directions is available.

[Paul McKenzie]

That's another way to do it, but there's still no way around an if statement determining which of the four directions is available.

That's true. Unless the OP is privy to something we're not aware of, there is no way to determine what directions are available without testing the return value in some way.

Regards,

Paul McKenzie

[AaronHod]

Thanks for the help guys, I'll have a play around again a bit later and let you know how I get on.

[Lindley]

Although the above is certainly more efficient, a conceptually simpler approach might be to store the directions as a std::string containing, for instance, "NSE" or "NW". (A C-style char[5] string is also an option here since there can be at most 4 directions.)

[AaronHod]

Create 4 const ints that represent north, south, east, and west. Number these ints, 1, 2, 4, and 8.

Then create a Node class that has a private unsigned int that holds the boolean OR of these values, denoting the possible directions.

const int NORTH = 1;
const int EAST = 2;
const int WEST = 4;
const int SOUTH = 8;

class Node
{
      unsigned int possibleDirections;
    public:      

          Node(unsigned d) : possibleDirections(d) { }
          unsigned int getDirections( ) const { return possibleDirections; }
};

int main()
{
   unsigned myDirections = NORTH | SOUTH;
   Node node1( myDirections );  // Node only goes north and south

   unsigned curDirections = node1.getDirections( );
   // how do you "parse" the directions out of the returned int?
}

I leave it to you to determine how to find the possible directions given the integer that is returned to you.

Regards,

Paul McKenzie

Just wondering why you used "1, 2, 4 and 8" here? Is there any significance in that?

[Paul McKenzie]

Just wondering why you used "1, 2, 4 and 8" here? Is there any significance in that?

Yes there is. Think of bits, bit patterns, and bit masks. What are the values of 1, 2, 4, and 8 in binary?

0001
0010
0100
1000

Does this give you a hint as to why I chose those numbers? Another hint -- why did I use a bitwise OR to combine the different directions? Yet another hint -- how do you determine if a certain bit is "on" or "off" (i.e. a certain direction is available or not)?

Regards,

Paul McKenzie

[TheCPUWizard]

Just wondering why you used "1, 2, 4 and 8" here? Is there any significance in that?

There is quite a BIT of significance...

[GCDEF]

FWIW, don't get hung up on this. You have four possibilities that may be any combination of yes or no. How you choose to represent those possibilities in your node class isn't really important. There's no getting around asking the thing teh equivalent of "can you move north" or "can you move south", so don't overthink it. You're only talking about a few lines of code and a few minutes of time.

[AaronHod]

Ok, i've given up with that method...
There must be a much simpler way to create this using a class and pointers?
Can somebody give me a little bit of help?
I want something like:

| Welcome to the Maze
| You are currently at "A"
| You can move EAST or SOUTH
| User Input: S
| You are currently at "B"
| You can move SOUTH or WEST

etc...

I just don't get it.

[TheCPUWizard]

You could always look here

and see how it was implemented in "C" about 13 years ago [there is an older Fortran version...]