Array of Objects

chr1zis · #1 20-Feb-2006, 14:57

Hello all. I am pretty new to C++ so I hope I can explain my problem. I am trying to create an array of objects. I want to read in a file that contains 1's and 0's and create an object for each 1 or 0. As I create each object I want to place them into an array. I think I have figured out how to read in the file and create the objects but I am having trouble putting them into an array. Please help! Thanks in advance.

Here is my code so far....

CPP / C++ / C Code:

class Cell {
public:
	Cell(int a) {
		value = a;
	}
private:
	int value;
};

int main()
{
    const int size = 10;
    int lifearray[size][size]; //constructing the 10x10 board
    int current;
        
    ifstream inLife("input.dat", ios::in); 
    ofstream outLife("output.dat", ios::out);
    
    if(!inLife)
    {
        cerr << "File could not be opened" << endl;
        exit(1);
    }    

    //for loop that reads in the file and constructs the array
    for(int i=0; i<10; i++)
    {
            for(int j=0; j<10; j++)
            {
                      inLife >> current;
					  Cell life(current);
                      lifearray[i][j] = current;
            }
    }

Chris.Dev · #2 20-Feb-2006, 15:07

You need to convert each byte to an int before it can be stored as an integer.

Firest declare current as a char array because 1 in ascii is 0x31 and 0 is 0x30.

Next you want to convert those input bytes respectively to 0x01 and 0x00 and store them in 4 bytes (an integer).

to do this i would use the atoi function declared in stdlib.h

so it would be:

CPP / C++ / C Code:

char current[size];
cin >> current;
lifearray[i][j] = atoi(current);

see a synopsis here: http://man.he.net/man3/atoi

chr1zis · #3 20-Feb-2006, 15:11

ignore this.. lifearray[i][j] = current;

i need to know how to create an array to where i can store the Cell objects...

Chris.Dev · #4 20-Feb-2006, 15:17

You can declare an array of classes just like any other type...

CPP / C++ / C Code:

#define MAX_CELLS 1000

class Cell *CELL[MAX_CELLS];

CELL[i] = new Cell(current);

chr1zis · #5 20-Feb-2006, 15:32

does this look right??

CPP / C++ / C Code:

const int size = 10;
    int lifearray[size][size]; //constructing the 10x10 board
    int current;
	class Cell *array[10][10];
        
    ifstream inLife("input.dat", ios::in); 
    ofstream outLife("output.dat", ios::out);
    
    if(!inLife)
    {
        cerr << "File could not be opened" << endl;
        exit(1);
    }    

    //for loop that reads in the file and constructs the array
    for(int i=0; i<10; i++)
    {
            for(int j=0; j<10; j++)
            {
                      inLife >> current;
                      array[i][j] = new Cell(current);
            }
    }

are you familiar with the game of life? http://www.bitstorm.org/gameoflife/ this is what i am trying to accomplish. i have already made the game using just the integer values and now i am trying to do it using objects.. how would i be able to use my 'play' function (which plays the game) if i am using objects.. here is the code.. thanks

CPP / C++ / C Code:

int play(int c[10][10], int size)
{
    if(!c)
    {
          cerr << "Board contains no live cells." << endl;
          exit(1);
    }
    
    int temp[10][10]; //temp array so the final values will not be altered
    
    for(int i=0; i<10; i++)
     {
        for(int j=0; j<10; j++)
        {
                temp[i][j] = c[i][j];
        }
     }
    
    int legalTurn = 0;
    int fitness = 0;
    int lastTurn = 0;
    bool anyLife = false;
  
    //for loop that goes through the array and sends the values to the
    //check function to determine if the cell should be alive or dead
    for(int x=0; x<100; x++)
    {
            for(int y=0; y<10; y++)
            {
                    for(int z=0; z<10; z++)
                    {
                            int living = check(c, y, z);
                            if(living > 0)
                            {
                                      temp[y][z] = 1;
                                      anyLife = true;
                                      if(x==100-1)
                                      {
                                                  lastTurn++;
                                      }
                            }
                            else 
                                 temp[y][z] = 0;
                    }
            }
            
            if(anyLife)
            {
                       legalTurn++;
            }
            
            anyLife = false;
            
            for(int i=0; i<10; i++)
            {
                    for(int j=0; j<10; j++)
                    {      
                           c[i][j] = temp[i][j];
                    }
            }
    }
    
    fitness = legalTurn * lastTurn;
    return fitness;
}

davekw7x · #6 20-Feb-2006, 15:39

Quote:

Originally Posted by chr1zis

i need to know how to create an array to where i can store the Cell objects...

CPP / C++ / C Code:

    const int size = 10;
    Cell cellArray[size][size]; //constructing the 10x10 array of Cells

(But you will need another constructor --- with no parameters)

CPP / C++ / C Code:

public:
  Cell(){};

Regards,

Dave

Chris.Dev · #7 20-Feb-2006, 15:54

Your first code group looks alright. I'm not quite sure what you mean be 'how can i use my play function' though. If you mean how can you pass the Cell object to the function there are several ways to do this. You could declare Cell as a global variable so all functions could access it or you could pass it as a variable to the function. The way I would do it though is to pass it by refrence.

Code:

int play(class Cell &CurrentCell);

chr1zis · #8 20-Feb-2006, 16:01

well my play function is set up to where i send it an array. is there any way i can still send it an array of class objects ??

Chris.Dev · #9 20-Feb-2006, 16:13

of course

CPP / C++ / C Code:


class Cell {
public:
	Cell(int a) {
		value = a;
	}
             int GetValue() { // since you declared value as private you
                                   // need a function to get its value
                 return value;
             }
private:
	int value;
};

int play(class Cell *cells) {
    int i;
    for(i=0;i<MAX_CELLS;++i) {
        //access the array just like any other
        cells[i].GetValue();
    }
}

chr1zis · #10 20-Feb-2006, 16:30

i have to copy the values into a temp array so the final values will not be altered.. when i do this..

CPP / C++ / C Code:

    for(int i=0; i<10; i++)
     {
        for(int j=0; j<10; j++)
        {
            temp[i][j] = cellArray[i][j].getValue();    
        }
     }

it gives me 2 errors on the line where i try to set the value that is in cellArray to the same spot in the temp array.. it says: 'class Cell' does not define this operator or a conversion to a type acceptable to the predefined operator. and it also says: '.getValue' must have class/struct/union type..

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Rate This Thread
Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pointer Usage in C++: Beginner to Advanced	varunhome	C++ Forum	0	19-Aug-2005 09:25
Merge and Heap...which is really faster	silicon	C++ Forum	0	10-May-2005 13:46
Help with an array using pointers	glulu76	C++ Forum	1	01-May-2005 11:21
template comiling problems - need expert debugger!	crq	C++ Forum	1	01-Feb-2005 21:26

Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects

Re: Array of Objects