Thread: text-based chess (with cursor selection feature)

thanks alot. here's the new code (only modification is changing board[7][7] declaration to board[8][8].

Code:

#include <iostream.h>
#include <conio.h>
#include <stdio.h>
#include <stdlib.h>

//let us write a single matrix chess program.

int i;
int j;
char command;
char board[8][8];
int xpos;
int ypos;
int pickupstate;
char cursor_storage;

void populator()
{
     for (i=0;i<8;i++)
     {
         for(j=0;j<8;j++)
         {
         board[i][j]='.';
         }
     } //seeds the board with periods as placeholders
     
     //the following is the specific placement of pieces; capital letters
     //represent white pieces, while the lowercase letters represent white
     //pieces.
     board[0][0]='r';
     board[0][1]='n';
     board[0][2]='b';
     board[0][3]='q';
     board[0][4]='k';
     board[0][5]='b';
     board[0][6]='n';
     board[0][7]='r';
     
     board[7][0]='R';
     board[7][1]='N';
     board[7][2]='B';
     board[7][3]='Q';
     board[7][4]='K';
     board[7][5]='B';
     board[7][6]='N';
     board[7][7]='R';
     
     for(i=0;i<8;i++)
     {
                     board[1][i]='p';
                     board[6][i]='P';
     }
     
     xpos=0;
     ypos=0;
     cursor_storage='*';
     pickupstate=0;
     //these are simply initial values.
}

void display()
{
     for(i=0;i<8;i++)
     {
                     for(j=0;j<8;j++)
                     {
                                     if(i!=ypos || j!=xpos)
                                     cout<<board[i][j];
                                     if(i==ypos && j==xpos)
                                     cout<<cursor_storage;
                     }
                     cout<<endl; 
                     //displays the board if the current coordinates
                     //being represented (i,j) are not in accordance with the
                     //'real coordinates' of where the cursor currently 'is'
                     //(ypos,xpos). if i and j are both equal to ypos/xpos 
                     //respectively, the character currently stored as the 
                     //cursor marker is displayed instead of board[i][j].
     }
     
}

void movement()
{
     command=getch();
     
     if(command=='w')//northward cursor movement
     {
                     ypos=ypos-1;
     }
     if(command=='s')//southward cursor movement
     {
                     ypos++;
     }                
     if(command=='a')//westward cusor movement
     {
                     xpos=xpos-1;
     }
     if(command=='d')//eastward cursor movement
     {
                     xpos++;
     }
     if(command=='k')//'k' is the button to pickup/release pieces currently on
                     //the board.
     {
                     if(pickupstate==0)//pickupstate of 0 indicates no piece
                                       //currently 'held' by the cursor
                     {
                                      cursor_storage=board[ypos][xpos];
                                      board[ypos][xpos]='.';
                                      pickupstate=1;
                     }
                     if(pickupstate==1)//pickupstate of 1 indicates a piece
                                       //is currently being held by cursor   
                     {
                                       board[ypos][xpos]=cursor_storage;
                                       cursor_storage='*';
                                       pickupstate=0;
                     }
     }
     system("cls"); //clears the after images to make it look like asingleboard
}
     
     int main()//now i just call in the three functions in an infinte loop.
               //press ctrl+c to terminate the program.
     {
         populator();
         for(;;)
         {
                display();
                movement();
         }
     
         return 0;
     }

y et i still can't get the "picking stuff up" to work...

First you check if(pickupstate==0), and inside that block you set pickupstate to 1. Then you check to see if pickupstate is 1. That will execute also. Perhaps you intended an else if or a plain old else.

BTW, your code won't compile on several modern compilers. You should switch from iostream.h to iostream, and make sure to account for the std namespace (a simple search of posts or the FAQ should give the details). Also, conio.h is non-standard, although there really isn't an alternative that does exactly what you want, so at this point you might as well leave it there. Finally, stdlib.h and stdio.h are standard C++ headers, but they don't look like they are needed in your program.

>> ypos=ypos-1;
ypos--; is a popular alternative


In your global declarations, I'd say initialise them all first, makes for safer and less undefined behaviour (look for Salem's sig). Most importantly say - int pickupstate=0;, I think, because it's undefined, so when you check to see if it's in the pick up state, it will more than likely not be what you want it to me. But it's always good practise to initialise variables anyways.


>> if(i!=ypos || j!=xpos)
>> cout<<board[i][j];
>> if(i==ypos && j==xpos)
>> cout<<cursor_storage;
why not just have it as -

if ( i==ypos && j==xpos ) cout<< whatever;
else cout<< the other alternative;

achieves the same end.

ahh... i overlooked the fact that the code "executes" from top-down and that the if pickupstate=1 conditional statement will be checked right after the if pickupstate=0 condition a few lines above it... thank you! i'll get to fixing that, then i'll write in some rules (limitations to movements of pieces and such... can;t have knights moving all over the board and crap! heh)

ty very much daved.

ok now one can play against another human! no rules have been yet implemented though

wasd= movement arrows
j = select piece/drop piece

Code:

#include <iostream.h>
#include <conio.h>
#include <stdio.h>
#include <stdlib.h>

//let us write a single matrix chess program.

int i;
int j;
char command;
char board[8][8];
int xpos=0;
int ypos=0;
int pickupstate=0;
char cursor_storage='*';

void populator()
{
     for (i=0;i<8;i++)
     {
         for(j=0;j<8;j++)
         {
         board[i][j]='.';
         }
     } //seeds the board with periods as placeholders
     
     //the following is the specific placement of pieces; capital letters
     //represent white pieces, while the lowercase letters represent white
     //pieces.
     board[0][0]='r';
     board[0][1]='n';
     board[0][2]='b';
     board[0][3]='q';
     board[0][4]='k';
     board[0][5]='b';
     board[0][6]='n';
     board[0][7]='r';
     
     board[7][0]='R';
     board[7][1]='N';
     board[7][2]='B';
     board[7][3]='Q';
     board[7][4]='K';
     board[7][5]='B';
     board[7][6]='N';
     board[7][7]='R';
     
     for(i=0;i<8;i++)
     {
                     board[1][i]='p';
                     board[6][i]='P';
     }
}

void display()
{
     for(i=0;i<8;i++)
     {
                     for(j=0;j<8;j++)
                     {
                                     if(i!=ypos || j!=xpos)
                                     cout<<board[i][j];
                                     if(i==ypos && j==xpos)
                                     cout<<cursor_storage;
                     }
                     cout<<endl; 
                     //displays the board if the current coordinates
                     //being represented (i,j) are not in accordance with the
                     //'real coordinates' of where the cursor currently 'is'
                     //(ypos,xpos). if i and j are both equal to ypos/xpos 
                     //respectively, the character currently stored as the 
                     //cursor marker is displayed instead of board[i][j].
     }
     
}

void movement()
{
     command=getch();
     switch(command)
     {
     case 'w'://northward cursor movement
                     ypos=ypos-1;
                     break;
     case 's'://southward cursor movement
                     ypos++;
                     break;             
     case 'a'://westward cusor movement
                     xpos=xpos-1;
                     break;
     case 'd'://eastward cursor movement
                     xpos++;
                     break;
     case 'j'://'k' is the button to pickup/release pieces currently on
                     //the board.             
                     switch(pickupstate)
                     {
                     case 1://pickupstate of 1 indicates a piece
                                       //is currently being held by cursor   
                                       board[ypos][xpos]=cursor_storage;
                                       cursor_storage='*';
                                       pickupstate=0;
                                       break;
                     case 0://pickupstate of 0 indicates no piece
                                       //currently 'held' by the cursor
                                      cursor_storage=board[ypos][xpos];
                                      board[ypos][xpos]='.';
                                      pickupstate=1;
                                      break;
                     default:
                     break;
                     }
     default:
             break;
     }
     system("cls"); //clears the after images to make it look like asingleboard
}
     
     int main()//now i just call in the three functions in an infinte loop.
               //press ctrl+c to terminate the program.
     {
         populator();
         for(;;)
         {
                display();
                movement();
         }
     
         return 0;
     }

>> In your global declarations, I'd say initialise them all first, makes for safer and less undefined behaviour.
Global variables are initialized for you, there is no undefined behavior. Although explicitly doing so might make the code clearer.

>> finally! i got it!
Nice work. If you're trying to learn C++, consider first passing values to your functions instead of having them be global. Then, once you get the hang of that you can try writing a class that encapsulates the chess board and game play.

what's a validation function?

i don;t understand alot of the jargon being thrown around... passing values to the functions? classes? i've heard of these but i haven;t the slightest when it comes to actually understanding what they mean.. could you explain (at least briefly)? if it's too complicated or something, you could just tell me to read up on them, but i'd rather someone tell it to me thanks.

oh, and i've heard somewhere that i shouldn;t use global variables and initializations... why? too clunky and un-fancy? just wondering

You'll learn the jargon over time. Global variables are not the best idea for several reasons. One is that they make it harder to re-use code. Your code doesn't have any great examples yet, but if you wanted to have two chessboards visible for some reason, your functions would have to be changed. If you actually sent the data for a board to the function, then you could call the function once for the first board and then again for the second board, and you wouldn't have to change the function code.

What I meant by passing values to functions was the use of function arguments. If you haven't learned about them yet, don't worry about it, but when you do (which should be soon) then try to use them instead of global variables.

As I look at your code I see you aren't using any local variables. When you only use a variable in a single function, you can create that variable inside that function. That will reduce the name clutter and help reduce programmer errors. For example, you don't use the command variable anywhere but inside of movement, so you could remove the char command; from the top of the file and change the first line of movement to be char command = getch();.

These are all somewhat minor details that you'll pick up as you go along, so don't worry too much about it.

nice program