How to check the surrounding numbers on a two dimensional array? - c++

Question

Hey so I want to create a text version of minesweeper. I created a grid that outputs ones and zeros(mines are represented by 0 and anything that is not a mine is a 1). How would I go about checking how many mines are around each non-mine (or how many 0's are around each number 1). Then updating the numbers to show how many mines are adjacent to them.
If someone could at least tell me where to start I would appreciate it :)
#include "pch.h"
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <iomanip>
#include <string>
using namespace std;
int main()
{
string mystring;
int grid[5][5] = {
{1, 1, 1, 1, 1},
{1, 1, 1, 1, 1},
{1, 1, 1, 1, 1},
{1, 1, 1, 1, 1},
{1, 1, 1, 1, 1}
};
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 5; j++)
{
int rNum = (rand() % 10) + 1;
if (rNum == 1 || rNum == 2)
{
grid[i][j] = 0; // mines are 0
}
else grid[i][j] = 1; // non-mines are represented by 1
std::cout << setw(4) << grid[i][j] << setw(4);
}
std::cout << std::endl;
}
}

Answer 1

I did a very similar thing in Java; although instead of representing the bombs with 0s I used 9s, because it is possible for a non-mine to be surrounded by 0 mines, it is not possible for one to be surrounded by 9 or higher mines. Here is my method:
for(int x = 0; x < 5; x++) {
for(int y = 0; y < 5; y++) {
if(grid[x][y] != 9) {
byte count = 0;
for(int lx = -1; lx <= 1; lx++) { //think of lx and ly as temporary x y
if((x+lx) >= 0 && (x+lx) < 5) {
for(int ly = -1; ly <= 1; ly++) {
if((y+ly) >= 0 && (y+ly) <5) {
if(grid[x+lx][y+ly] == 9) {
count += 1;
}
}
}
}
}
grid[x][y] = count;
}
}
}
Basically what it does is it scrolls through each point on the grid, checking if it is a bomb. If it is not, it checks each of the 8 squares touching it(as long as they are in the bounds of the grid, don't want an undefined index error). Then if they are a bomb it adds one to the count. Finally, it sets the number on the tile equal to the count of touching bombs.

Answer 2

In my case I pass pointer to 2d array of type wchar_t but can be any type as you want. Assuming that you have 2d array, you can refer to each cell by [X,Y] but also you need to check if the cell have all neighbours (for example left top cell of table have only 3 neighbours):
void getNeighbours(wchar_t* scr,int x, int y)
{
// Left
if((x-1)>=0)
{
// value = scr[getIndex(x-1,y)];
}
// Right
if((x+1)<tableWidth)
{
// value = scr[getIndex(x+1,y)];
}
//Up
if((y-1)>=0)
{
// value = scr[getIndex(x,y-1)];
}
//Down
if((y+1)<tableHeight)
{
// value = scr[getIndex(x,y+1)];
}
// Left down
if((x-1)>=0 && ((y-1)>=0))
{
// value = scr[getIndex(x-1,y+1)];
}
// Right Down
if((x+1)<tableWidth && (y+1)<tableHeight)
{
// value = scr[getIndex(x+1,y+1)];
}
// Right UP
if((x+1)<tableWidth && (y-1)>=0)
{
// value = scr[getIndex(x+1,y-1)];
}
// Left Up
if((x-1)>=0 && (y-1)>=0)
{
// value = scr[getIndex(x-1,y-1)];
}
}
getIndex() function to get index of cell indicated by [X,Y]:
int getIndex(int x, int y)
{
return (tableWidth*y+x);
}