TicTacToe in, manual win detection

#include <stdio.h>

int i;
int j;
int l;
int h;
int u;
int z;

int x;
int y;
//board[x][y]
//board[rows][columns]
int board[3][3] = {
    {0, 0, 0} ,//Initializers for row 0
    {0, 0, 0} ,//Initializers for row 1
    {0, 0, 0}//initializers for row 2
};

int cell;

/*
0 = not filled yet
1 = O
2 = X
*/

/*Board will not be an array itself. array will just be used for saving.
[O][X][O]
[X][0][0]
[O][X][X]
*/

//function declaration
void display();
void p1();
void p2();

main(){
    system("clear");

    display();

    p1();
    for(u = 0; u <= 3; u++){
        p2();
        p1();
    }
}

void display(){
    system("clear");

    for(i = 0; i <= 2; i++){
        for(j = 0; j <= 2; j++){
            cell = board[i][j];
            switch(cell){
                case 0: printf("[_]");
                    break;
                case 1: printf("[O]");
                    break;
                case 2: printf("[X]");
                    break;
                default:printf("[!]");
            }
        }
        printf("\n");
    }
    printf("\n");
}

void p1(){
    printf("It's P1's turn[O].\n");
    printf("Enter row to enter symbol in: ");
    scanf("%d", &x);

    printf("\nEnter column to enter symbol in: ");
    scanf("%d", &y);

    board[x][y] = 1;

    x, y = 0;

    display();
}

void p2(){
    printf("It's P2's turn[X].\n");
    printf("Enter row to enter symbol in: ");
    scanf("%d", &x);

    printf("\nEnter column to enter symbol in: ");
    scanf("%d", &y);

    board[x][y] = 2;

    x, y = 0;

    display();
}