Tic Tac Toe- help and advice

[PoBurly]

I am making a tic tac toe game with competitive AI and having quite a bit of trouble. I can't figure out exactly where the problem is coming from and I have been messing with it for about a week now. The game plays correctly with two players but I'm having trouble with the AI part. The computer doesn't play outside of it's initial move unless there is an opportunity for either player to win. I had it running a little better previously but after rearranging the code so much I forgot how I had it. I am a beginner so any help and recommendations would be nice.

A side question I had was: is there any way to set up the computer's AI how I have it without typing every line. I'm looking for a shorter and concise alternative so it doesn't take up so many lines.

#include <iostream>
#include "System&TwoPlayers.h"

void gameMenu();
void compTurn();
void computerOponent();
void endGameC();
void intelligence();
void compWin();
char playerComp = 'O';
char playChoice = '9';

int main() {
	cout << "Would you like to play tic tac toe?" << endl
	<< "If so, press 'y', if not, press 'q' to quit." << endl;
	char play;
	cin >> play;
	if (play == 'y'){
		gameMenu();
	}
	if (play == 'q'){
		cout << "Goodbye." << endl;
}
}
void gameMenu(){
	cout << "Would you like to play tic tac toe against another player(p) or " <<
	"a computer(c)?" << endl;
	char gameChoice;
	cin >> gameChoice;
	if (gameChoice == 'p'){
		turnRotate();
	}
	else if (gameChoice == 'c'){
		computerOponent();
	}
	else{
		cout << "That is not a option." << endl;
		gameMenu();
	}
}

void computerOponent(){
	while (!win & !draw){
		if (turn){
			cout << "Player one, it is your turn." << endl
			<< "Press the number in the space you want to move." << endl;
			grid();
			mark = playerOne;
			playTurn();
			winCondition();
			turn = !turn;
	}
		else{
			mark = playerComp;
			compTurn();
			winCondition();
			turn = !turn;
			sleep(1);
		}
	}
	endGameC();
}

void compTurn(){
		intelligence();
		compWin();
		if ( playChoice == placement[0]){
			placement[0] = mark;
	}
		else if (playChoice == placement[1]){
			placement[1] = mark;
	}
		else if (playChoice == placement[2]){
			placement[2] = mark;
	}
		else if (playChoice == placement[3]){
			placement[3] = mark;	
	}
		else if (playChoice == placement[4]){
			placement[4] = mark;	
	}
		else if (playChoice == placement[5]){
			placement[5] = mark;	
	}
		else if (playChoice == placement[6]){
			placement[6] = mark;	
	}
		else if (playChoice == placement[7]){
			placement[7] = mark;	
	}
		else if (playChoice == placement[8]){
			placement[8] = mark;	
	}
		else{
			int variableConverter = playChoice - '0';
			variableConverter--;
			playChoice = variableConverter + '0';
		}
}

void endGameC(){
	if (win){
		if (mark == playerOne){
			grid();
			cout << "Congratulations. Player one has won the game." << endl;
		}
		if (mark == playerComp){
			grid();
			cout << "Yeah, that's right. I won the game!" << endl;
		}
	}
	if (draw){
		grid();
		cout << "Tie Game. There is no winner." << endl;
	}

}

void intelligence(){			////  order of code for computer placements:row1, row2, row3, column1, column2, column3,4diags
	if (placement[0] == playerOne & placement[1] == playerOne){			//// row 1 
		playChoice = '3';
	}
	if (placement[1] == playerOne & placement[2] == playerOne){
		playChoice = '1';
	}
	if (placement[0] == playerOne & placement[2] == playerOne){
		playChoice = '2';
	}
	if (placement[3] == playerOne & placement[4] == playerOne){			//// row 2
		playChoice = '6';
	}
	if (placement[4] == playerOne & placement[5] == playerOne){
		playChoice = '4';
	}
	if (placement[3] == playerOne & placement[5] == playerOne){
		playChoice = '5';
	}
	if (placement[6] == playerOne & placement[7] == playerOne){			//// row 3
		playChoice = '9';
	}
	if (placement[7] == playerOne & placement[8] == playerOne){
		playChoice = '7';
	}
	if (placement[6] == playerOne & placement[8] == playerOne){
		playChoice = '8';
	}
	if (placement[0] == playerOne & placement[3] == playerOne){			////column 1
		playChoice = '7';
	}
	if (placement[3] == playerOne & placement[6] == playerOne){
		playChoice = '1';
	}
	if (placement[0] == playerOne & placement[6] == playerOne){
		playChoice = '4';
	}
	if (placement[1] == playerOne & placement[4] == playerOne){			////column 2
		playChoice = '8';
	}
	if (placement[4] == playerOne & placement[7] == playerOne){
		playChoice = '2';
	}
	if (placement[1] == playerOne & placement[7] == playerOne){
		playChoice = '5';
	}
	if (placement[2] == playerOne & placement[5] == playerOne){			////column 3
		playChoice = '8';
	}
	if (placement[5] == playerOne & placement[8] == playerOne){
		playChoice = '3';
	}
	if (placement[2] == playerOne & placement[8] == playerOne){
		playChoice = '6';
	}
	if (placement[0] == playerOne & placement[4] == playerOne){			////diags
		playChoice = '9';
	}
	if (placement[2] == playerOne & placement[4] == playerOne){
		playChoice = '7';
	}
	if (placement[6] == playerOne & placement[4] == playerOne){
		playChoice = '3';
	}
	if (placement[8] == playerOne & placement[4] == playerOne){
		playChoice = '1';
	}
	if (placement[0] == playerOne & placement[8] == playerOne){
		playChoice = '5';
	}
	if (placement[2] == playerOne & placement[6] == playerOne){
		playChoice = '5';
	}
}

void compWin(){			////  order of code for computer placements:row1, row2, row3, column1, column2, column3,4diags
	if (placement[0] == playerComp & placement[1] == playerComp){			//// row 1
		playChoice = '3';
	}
	if (placement[1] == playerComp & placement[2] == playerComp){
		playChoice = '1';
	}
	if (placement[0] == playerComp & placement[2] == playerComp){
		playChoice = '2';
	}
	if (placement[3] == playerComp & placement[4] == playerComp){			//// row 2
		playChoice = '6';
	}
	if (placement[4] == playerComp & placement[5] == playerComp){
		playChoice = '4';
	}
	if (placement[3] == playerComp & placement[5] == playerComp){
		playChoice = '5';
	}
	if (placement[6] == playerComp & placement[7] == playerComp){			//// row 3
		playChoice = '9';
	}
	if (placement[7] == playerComp & placement[8] == playerComp){
		playChoice = '7';
	}
	if (placement[6] == playerComp & placement[8] == playerComp){
		playChoice = '8';
	}
	if (placement[0] == playerComp & placement[3] == playerComp){			////column 1
		playChoice = '7';
	}
	if (placement[3] == playerComp & placement[6] == playerComp){
		playChoice = '1';
	}
	if (placement[0] == playerComp & placement[6] == playerComp){
		playChoice = '4';
	}
	if (placement[1] == playerComp & placement[4] == playerComp){			////column 2
		playChoice = '8';
	}
	if (placement[4] == playerComp & placement[7] == playerComp){
		playChoice = '2';
	}
	if (placement[1] == playerComp & placement[7] == playerComp){
		playChoice = '5';
	}
	if (placement[2] == playerComp & placement[5] == playerComp){			////column 3
		playChoice = '8';
	}
	if (placement[5] == playerComp & placement[8] == playerComp){
		playChoice = '3';
	}
	if (placement[2] == playerComp & placement[8] == playerComp){
		playChoice = '6';
	}
	if (placement[0] == playerComp & placement[4] == playerComp){			////diags
		playChoice = '9';
	}
	if (placement[2] == playerComp & placement[4] == playerComp){
		playChoice = '7';
	}
	if (placement[6] == playerComp & placement[4] == playerComp){
		playChoice = '3';
	}
	if (placement[8] == playerComp & placement[4] == playerComp){
		playChoice = '1';
	}
	if (placement[0] == playerComp & placement[8] == playerComp){
		playChoice = '5';
	}
	if (placement[2] == playerComp & placement[6] == playerComp){
		playChoice = '5';
	}
}

[xismn]

On line 43, you've written this:
while (!win & !draw){

which doesn't do what you think it does.

& is the bitwise AND operator.

&& is the binary AND operator, which is what you want.

EDIT* ironically, this makes no difference.

[PoBurly]

Yeah I have noticed that. I messed around with it for a while because I thought it needed to be || or |, but then realized the same thing you did.

Thanks though.