Tic Tac Toe resetting the board after the 3rd move - c

Question

So everything works fine till the 4th move. It then resets the board and puts and X in the first box. What's wrong with it? Also I would prefer if I would be guided to the answer, not just given it, it's for the learning. I've also tried finding the answer without any help by cutting one part and checking what effect it does. (Don't know how to use the debugger cause it always gives out, filename has no debugging information).
#include <stdio.h>
#include <stdlib.h>
int clear(void);
int displayboard(void);
int initialize(void);
int startgame(void);
int checkwin(char);
int canwin(void);
int getmove(void);
int makemove(void);
int canblock(void);
char board[3][3];
int main()
{
int menuchoice;
while(1)
{
printf(" |\\ /| | | /\\ |\\ |\n");
printf(" | \\/ | | | /--\\ | \\ |\n");
printf(" | | | |_ / \\ | \\|\n");
printf(" Tic-tac-toe Version 1 \n\n");
printf(" [Main Menu]\n");
printf(" 1 - Start game\n");
printf(" 2 - Exit game\n");
scanf("%d",&menuchoice);
if(menuchoice==1)
{
clear();
startgame();
}
else if(menuchoice==2)
{
exit(EXIT_SUCCESS);
}
}
}
/* Prints newlines to refresh the page */
int clear(void)
{
int i;
for(i=0;i<25;i++)
{
printf("\n");
}
return 0;
}
/* Makes the board blank */
int initialize(void)
{
int numrow,numcol;
numrow=0;
numcol=0;
while(numrow<3)
{
while(numcol<3)
{
board[numrow][numcol]=' ';
numcol++;
}
numcol=0;
numrow++;
}
return 0;
}
/* Prints the board */
int displayboard(void)
{
printf(" 1 2 3\n\n\n");
printf(" 1 %c | %c | %c \n",board[0][0],board[0][1],board[0][2]);
printf(" ------------- \n");
printf(" 2 %c | %c | %c \n",board[1][0],board[1][1],board[1][2]);
printf(" ------------- \n");
printf(" 3 %c | %c | %c \n",board[2][0],board[2][1],board[2][2]);
return 0;
}
/* Function that controls the game*/
int startgame(void)
{
int movecount;
while(1)
{
movecount=0;
initialize();
displayboard();
board[1][1]='X';
clear();
displayboard();
getmove();
makemove();
movecount=3;
while(1)
{
clear();
displayboard();
getmove();
/* I believe the problem starts here */
if(checkwin('O')==1)
{
printf("\n\t\t\tYou WIN!!!!");
/*just to test*/
exit(EXIT_SUCCESS);
}
movecount++;
canwin(); /* Checks if it can make winning move */
if(canblock()==0) /*if a move to block has not been made*/
{
makemove();
movecount++;
}
else if(canblock()==1) /*if a move to block has been made*/
{
movecount++;
}
if(checkwin('X')==1)
{
printf("\n\t\t\tYou LOSE!!!");
/* just to test */
exit(EXIT_SUCCESS);
}
if(movecount==9)
{
printf(" Its a DRAW!!!");
/*Just to test */
exit(EXIT_SUCCESS);
}
}
}
}
/* Function to check win */
int checkwin(char ltr)
{
int rownumber,colnumber;
for(rownumber=0;rownumber<3;rownumber++)
{
if(board[rownumber][0]==ltr && board[rownumber][1]==ltr && board[rownumber][2]==ltr)
{
return 1;
}
}
for(colnumber=0;colnumber<3;colnumber++)
{
if(board[0][colnumber]==ltr && board[1][colnumber]==ltr && board[2][colnumber]==1)
{
return 1;
}
}
if(board[0][0]==ltr && board[1][1]==ltr && board[2][2]==ltr)
{
return 1;
}
else if(board[0][2]==ltr && board[1][1]==ltr && board[2][0]==ltr)
{
return 1;
}
else
return 0;
}
/* Function to get move */
int getmove(void)
{
int colnumber,rownumber;
printf("\n\t\t\tWhat row do you want to put your move?\n");
scanf("%d",&rownumber);
printf("\n\t\t\tWhat column do you want to put your move?\n");
scanf("%d",&colnumber);
board[rownumber-1][colnumber-1]='O';
return 0;
}
/* Function to makemove */
int makemove(void)
{
if(board[0][0]==' ')
{
board[0][0]='X';
return 0;
}
else if(board[0][2]==' ')
{
board[0][2]='X';
return 0;
}
else if(board[2][0]==' ')
{
board[2][0]='X';
return 0;
}
else if(board[2][2]==' ')
{
board[2][2]='X';
return 0;
}
else if(board[0][1]==' ')
{
board[0][1]=='X';
return 0;
}
else if(board[1][0]==' ')
{
board[1][0]='X';
return 0;
}
else if(board[1][2]==' ')
{
board[1][2]='X';
return 0;
}
else if(board[2][1]==' ')
{
board[2][1]='X';
return 0;
}
}
/* Function to make winning move */
int canwin(void)
{
int rownumber,colnumber;
for(rownumber=0;rownumber<3;rownumber++)
{
for(colnumber=0;colnumber<3;colnumber++)
{
board[rownumber][colnumber]='X';
if(checkwin('X')==1)
{
return 1;
}
board[rownumber][colnumber]=' ';
}
}
return 0;
}
/* Function to block winning move */
int canblock(void)
{
int rownumber,colnumber;
for(rownumber=0;rownumber<3;rownumber++)
{
for(colnumber=0;colnumber<3;colnumber++)
{
board[rownumber][colnumber]='O';
if(checkwin('O')==1)
{
board[rownumber][colnumber]='X';
return 1;
}
else if(checkwin('O')==0)
{
board[rownumber][colnumber]=' ';
}
}
}
return 0;
}

Answer 1

I think you got a problem in your canwin() function, as I understand it, you want the A.I. to test if it can make a winning move. But looking at the function
int canwin(void)
{
int rownumber,colnumber;
for(rownumber=0;rownumber<3;rownumber++)
{
for(colnumber=0;colnumber<3;colnumber++)
{
board[rownumber][colnumber]='X'; // <--- Problem here
if(checkwin('X')==1)
{
return 1;
}
board[rownumber][colnumber]=' ';
}
}
return 0;
}
You are actually overwriting current position of your board with an 'X', without checking if there already was a symbol there before! So you are essentially overwriting your board with 'X'es, checking if the X-player won and if not "resetting" to empty space ' '!
You can fix this by inserting a check before your write like this:
if (board[rownumber][colnumber] == ' ')
{
board[rownumber][colnumber]='X';
...