How to validate a move in a checkerboard C? - c

Question

Hi im a newbie at programming and this task is frustrating me rn because I still can't get the piece to move on the board. I am guessing this has to do on my while loop function but still can't get it right. The 1st user input should detect the coordinate of the character to move and show what are the available spots to where it can send the piece using validateMove(). Here's my code, Been onto this for weeks now.
#include <stdio.h>
char board[8][8] = {
{' ', 'B', ' ', 'B', ' ', 'B', ' ', 'B'},
{'B', ' ', 'B', ' ', 'B', ' ', 'B', ' '},
{' ', 'B', ' ', 'B', ' ', 'B', ' ', 'B'},
{'*', ' ', '*', ' ', '*', ' ', '*', ' '},
{' ', '*', ' ', '*', ' ', '*', ' ', '*'},
{'W', ' ', 'W', ' ', 'W', ' ', 'W', ' '},
{' ', 'W', ' ', 'W', ' ', 'W', ' ', 'W'},
{'W', ' ', 'W', ' ', 'W', ' ', 'W', ' '}};
void printBoard()
{
int i , j , k ;
printf("\n ");
for(i=0;i<8;i++)
printf(" %d", i+1 );
printf(" \n");
for(k=0;k<8;k++)
{
printf(" ");
for(i=0;i<42;i++)
{
printf("-");
}
printf(" \n");
printf(" %d ", k+1);
for(j=0;j<8;j++)
{
printf("|| %c ", board[k][j]);
}
printf("|| \n");
}
printf(" ");
for(i=0;i<42;i++)
{
printf("-");
}
printf(" \n");
}
void validateMoveChecker(int x1, int y1, int af, int bf, int v)
{
int a, b;
for(a=1, b=1; board[x1+ af * a][y1+ bf * b] == '*'; a++, b++)
{
if((x1+af*a) == -1 || (y1+bf*b)==v)
return;
printf("%d%d , ", x1+af*a , y1+bf*b);
}
}
int validateMove(int x1 , int y1)
{
printf( "Available coordinates to send the piece are: \n" );
validateMoveChecker(x1, y1, -1, 1, 8);
validateMoveChecker(x1, y1, 1, -1, -1);
validateMoveChecker(x1, y1, 1, 1, 8);
validateMoveChecker(x1, y1, -1, -1, -1);
}
int getChange(int x1 ,int y1 ,int x2 ,int y2 )
{
char temp;
temp = board[x1][y1];
board[x1][y1] = board[x2][y2];
board[x2][y2] = temp;
}
int check(int x, int y)
{
switch(board[x][y])
{
case 'B':
return 1;
break;
default:
return 0;
}
}
int main(){
int x1, y1, x2, y2, pos1, pos2, x, y;
char board[8][8];
printBoard();
do
{
printf("\nEnter the position of the piece [X,Y]: ");
scanf("%d", &pos1);
y1 = pos1%10;
x1 = pos1/10;
switch(board[x1][y1])
{
case 'B': validateMove(x1, y1);
break;
default: printf("Invalid Position. Please enter again!");
}
}while(x1!=0 && y1!=0);
printf("\nEnter the position on where to send the piece [X,Y]: ");
scanf("%d", &pos2);
y2 = pos2%10;
x2 = pos2/10;
getChange(x1 ,y1 ,x2 ,y2);
if((x2-x1==y2-y1)!=0)
{
getChange(x1 ,y1 ,x2 ,y2);
check(x,y);
}
}

Answer 1

I changed printBoard() to show index starting with 0 (1 is fine too, but then you need to adjust indexes):
void printBoard() {
int i , j , k ;
printf("\n ");
for(i=0;i<8;i++)
printf(" %d", i );
printf(" \n");
for(k=0;k<8;k++) {
printf(" ");
for(i=0;i<42;i++) {
printf("-");
}
printf(" \n");
printf(" %d ", k);
for(j=0;j<8;j++) {
printf("|| %c ", board[k][j]);
}
printf("|| \n");
}
printf(" ");
for(i=0;i<42;i++) {
printf("-");
}
printf(" \n");
}
and then in main() I made the following changes:
removed the local variable board; your code relies on a global variable of the same name. It would, however, be a better design to pass board to the functions that need it instead of using a global variable.
changed the two scanf() to just read the coordinates directly.
added a printBoard() after getChange() to verify the move worked.
(not fixed) the variables x and y are uninitialized.
int main(void) {
int x1, y1, x2, y2, x, y;
printBoard();
do {
printf("\nEnter the position of the piece [X,Y]: ");
scanf("%d,%d", &x1, &y1);
switch(board[x1][y1]) {
case 'B':
validateMove(x1, y1);
break;
default:
printf("Invalid Position. Please enter again!");
}
} while(x1 && y1);
printf("\nEnter the position on where to send the piece [X,Y]: ");
scanf("%d,%d", &x2, &y2);
getChange(x1, y1 ,x2 ,y2);
printBoard();
if((x2-x1==y2-y1)!=0) {
getChange(x1 ,y1 ,x2 ,y2);
check(x, y);
}
}
and example session:
0 1 2 3 4 5 6 7
------------------------------------------
0 || || B || || B || || B || || B ||
------------------------------------------
1 || B || || B || || B || || B || ||
------------------------------------------
2 || || B || || B || || B || || B ||
------------------------------------------
3 || * || || * || || * || || * || ||
------------------------------------------
4 || || * || || * || || * || || * ||
------------------------------------------
5 || W || || W || || W || || W || ||
------------------------------------------
6 || || W || || W || || W || || W ||
------------------------------------------
7 || W || || W || || W || || W || ||
------------------------------------------
Enter the position of the piece [X,Y]: 0,1
Available coordinates to send the piece are:
Enter the position on where to send the piece [X,Y]: 0,0
0 1 2 3 4 5 6 7
------------------------------------------
0 || B || || || B || || B || || B ||
------------------------------------------
1 || B || || B || || B || || B || ||
------------------------------------------
2 || || B || || B || || B || || B ||
------------------------------------------
3 || * || || * || || * || || * || ||
------------------------------------------
4 || || * || || * || || * || || * ||
------------------------------------------
5 || W || || W || || W || || W || ||
------------------------------------------
6 || || W || || W || || W || || W ||
------------------------------------------
7 || W || || W || || W || || W || ||
------------------------------------------