TicTacToe board problem

[Overlord]

Hello, i'm having a problem with a tic tac toe game. If CPU tries to put 'O' where already is 'O' or 'X', the program crashes.

/*Here is the board, each letter is a variable
  a | b  | c
____|____|____
  d | e  | f  
____|____|____
  g | h  | i  
    |    |    
*/

void CPUp() //function to put in CPU's choice
{
cgennum(); //generates random number for variable cpu_line
     
switch(cpu_line)
{
                case 1: if(a=='a') a = 'O'; else {again();} break;
                case 2: if(b=='b') b = 'O'; else {again();} break;
                case 3: if(c=='c') c = 'O'; else {again();} break;
                case 4: if(d=='d') d = 'O'; else {again();} break;
                case 5: if(e=='e') e = 'O'; else {again();} break;
                case 6: if(f=='f') f = 'O'; else {again();} break;
                case 7: if(g=='g') g = 'O'; else {again();} break;
                case 8: if(h=='h') h = 'O'; else {again();} break;
                case 9: if(i=='i') i = 'O'; else {again();} break;
}
}

void again() //function to generate another number if the current slot is already full
{
cpu_line = backup;
while (cpu_line == backup)
{
      cgennum();
} //when cpu_line changes, try to put 'O' again
CPUp();
}

I hope you understand me, any help would be grateful. If you want, I can post the whole source code here.

[Mario F.]

cpu_line = backup;
while (cpu_line == backup)
{
      cgennum();
}

This while loop never ends.

EDIT: Actually it may end, assuming cpu_line and backup are globals... Can you show the definition of cgennum()?

[twomers]

It would probably be easier too if you labelled the elements of the TTT game area from 0 to 8 (or 1 to 9). I see why you used letters though.

How long is the whole source?

[Overlord]

Here it is, all the code. Compile it, it works, but the program crashes when CPU attempts to put in 'O', where it already is.

#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;



const int LOW = 1;
const int HIGH = 9;
char location;
char location1;
char winningsuccess='y';
char state='n';
int cpu_line;
int backup;
int q=0;
char a = 'a', b = 'b', c = 'c', d = 'd', e = 'e', f = 'f', g = 'g', h = 'h', i = 'i';



void showmap();
void cgennum();
void check();
void again();
void user();
void CPUp();

/*laukums

cout<<"  a | b  | c
cout<<"____|____|____"<<endl;
cout<<"  d | e  | f  "<<endl;
cout<<"____|____|____"<<endl;
cout<<"  g | h  | i  "<<endl;
cout<<"    |    |    "<<endl;
*/


int main()

{cout<<"Sveicinati spele desas!\nSaciet spelet!\n\n";
do{


showmap();

cin>>location;

cin.ignore();

system("cls");

user();

CPUp();

check();


} while (state!=winningsuccess);
showmap();
cout<<"Uzvara!";
cin.get();
return 1;
}

void showmap()
{
cout<<"laukuma karte:\n";
cout<<"  "<<a<<" | "<<b<<"  | "<<c<<" "<<endl;
cout<<"____|____|____"<<endl;
cout<<"  "<<d<<" | "<<e<<"  | "<<f<<"  "<<endl;
cout<<"____|____|____"<<endl;
cout<<"  "<<g<<" | "<<h<<"  | "<<i<<"  "<<endl;
cout<<"    |    |    \n";
}

void user()
{
switch(location)
{
                case 'a': if(a=='a') a = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'b': if(b=='b') b = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'c': if(c=='c') c = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'd': if(d=='d') d = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'e': if(e=='e') e = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'f': if(f=='f') f = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'g': if(g=='g') g = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'h': if(h=='h') h = 'X'; else cout<<"Tur jau ir ielikts"; break;
                case 'i': if(i=='i') i = 'X'; else cout<<"Tur jau ir ielikts"; break;
}
}

void cgennum() //changes cpu_line
{
time_t seconds;
time(&seconds);
srand((unsigned int)seconds);
cpu_line = rand() % ( HIGH - LOW + 1) + LOW;
}

void CPUp()
{
cgennum();
     
     switch(cpu_line)
{
                case 1: if(a=='a') a = 'O'; else {again();} break;
                case 2: if(b=='b') b = 'O'; else {again();} break;
                case 3: if(c=='c') c = 'O'; else {again();} break;
                case 4: if(d=='d') d = 'O'; else {again();} break;
                case 5: if(e=='e') e = 'O'; else {again();} break;
                case 6: if(f=='f') f = 'O'; else {again();} break;
                case 7: if(g=='g') g = 'O'; else {again();} break;
                case 8: if(h=='h') h = 'O'; else {again();} break;
                case 9: if(i=='i') i = 'O'; else {again();} break;
}
}

void again()
{
cpu_line = backup;
while (cpu_line == backup)
{
      cgennum();
}
CPUp();
}

void check()
{
     if((a==b && b==c) || (d==e && e==f) || (g==h && h==i) || (a==d && d==g) || (b==e && e==h) || (c==f && f==i) || (a==e && e==i) || (g==e && e==c))
     state = 'y';
}

[Mario F.]

Ugh! you really have to review your indentation policy

Anyways, the program flow seems faulty. When the computer makes his move, it generates a random number between 1 and 9. It checks that location. If there is something there already (0 or X) it calls again(). Again() generates a new number and calls the CPup() again... but yet a new number is generated at the top of CPUp()...

[Daved]

You don't need again(), just make a loop inside CPUp.

Also, you should only be calling srand once, at the beginning of your program.

[mrafcho001]

I wrote this TTT a while ago when i was learning...
http://martin.thejefffiles.com/TTT.rar

[Overlord]

I tried with a loop, the same...

void CPUp()
{
cgennum();
     
     switch(cpu_line)
{
                case 1: if(a=='a') a = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 2: if(b=='b') b = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 3: if(c=='c') c = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 4: if(d=='d') d = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 5: if(e=='e') e = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 6: if(f=='f') f = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 7: if(g=='g') g = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 8: if(h=='h') h = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
                case 9: if(i=='i') i = 'O'; else {cpu_line = backup; while (cpu_line == backup){CPUp();}} break;
}
}

If my loop isn't correct, just say.

[Daved]

No, don't call any function, just put the whole thing in a single loop. There is no need for backup either. If the space is unoccupied, then return from the function, otherwise the loop will continue.

[CrazedBrit]

Shouldn't this

cpu_line = backup;

be

backup = cpu_line;

Because backup never gets initiated. And i'm guessing that the while(cpu_line==backup) loop is supposed to keep looping until you get something for cpu_line that isn't the value you just tried. So therefore you want backup to equal the value that cpu_line just had. Make sense?

[Overlord]

Thanks man! Now the program works! Thanks to you all! Now you can add another working ticTacToe game to your collection.

[CrazedBrit]

Haha that makes two
Glad I could help

[Daved]

Now that its working, you should consider trying to get rid of the again() function as an exercise. That design will cause problems if you use it more complex games (if there is only one space left you could easily get a stack overflow). It shouldn't be too hard to get it to work with a single while loop, so it might be worth it to try.