How to check for neighbors in Game of Life C++? - c++

Question

I am working on an assignment for school and of course I receive very vague feedback on our code. The code I am working on is for Conway's Game of Life. I know I am super close. I have code that prints out the new generation but it's definitely not the correct one. It seems it is not counting the neighbors correctly - what should be identified as an alive neighbor doesn't seem to happen.
From our assignment as well (seeing examples of generations being formed) I notice the border cells do change which means I have to access them without going out of bounds. I feel I have been fruitless in my attempts to do this and I think I'm just missing something super obvious.
Please, any feedback would be amazing.
I have several print lines in attempts of debugging.
void gameOfLife(vector<vector<string>> &originalGrid, vector<vector<string>> &grid, int row, int col,
int Rows, int Cols){
//counts # of alive neighbors
int aliveNeighbors = 0;
string alive = "*";
for(int posX = row-1; posX <= row+1; posX++){
for(int posY = col-1; posX <= col+1; posX++){
std::cout << "I am in function - nested loop " << row << " " << col << std::endl;
if(posX == row && posY == col){
continue;
}
else if((posX >= 0 && posX < Rows) && (posY >= 0 && posY < Cols)){
std::cout << "I am in function - nested loop - else if " << row << " " << col << std::endl;
if(grid[posX][posY] == alive){
aliveNeighbors++;
std::cout << "alive neighbors: " << aliveNeighbors << std::endl;
}
}
}
}
/*
//top cell
if(grid[row][col-1] == "*"){
std::cout << "top cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//bottom cell
if(grid[row][col+1] == "*"){
std::cout << "bottom cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//left cell
if(grid[row-1][col] == "*"){
std::cout << "left cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//right cell
if(grid[row+1][col] == "*"){
std::cout << "right cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//top left
if(grid[row-1][col-1] == "*"){
std::cout << "top left cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//top right
if(grid[row+1][col-1] == "*"){
std::cout << "top right cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//bottom left
if(grid[row-1][col+1] == "*"){
std::cout << "bottom left cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
//bottom right
if(grid[row+1][col+1] == "*"){
std::cout << "bottom right cell " << row << " " << col << std::endl;
aliveNeighbors++;
}
*/
//test cases
//test case 1: Any live cell with fewer than two live neighbors dies (as if by underpopulation).
if(grid[row][col] == alive && aliveNeighbors < 2){
originalGrid[row][col] = ".";
}
//test case 2: Any live cell with more than three live neighbors dies (as if by overpopulation/overcrowding).
if(grid[row][col] == alive && aliveNeighbors > 3){
originalGrid[row][col] = ".";
}
//test case 3: Any live cell with two or three live neighbors lives, unchanged, to the next generation.
if(grid[row][col] == alive && (aliveNeighbors == 3 || aliveNeighbors == 2)){
originalGrid[row][col] = grid[row][col];
}
//test case 4: Any dead cell with exactly three live neighbors will come to life (as if by reanimation or birth).
if(grid[row][col] == "." && aliveNeighbors == 3){
originalGrid[row][col] = alive;
}
//prints updated grid
for(int i = 0; i < Rows; i++){
for(int j = 0; j < Cols; j++){
std::cout << originalGrid[i][j] << " ";
}
std::cout << std::endl;
}
std::cout << std::endl;
return;
}
int main() {
int rows, col, numOfGen;
std::cin >> rows >> col >> numOfGen;
string cell;
vector<vector<string>> game;
for(int i = 0; i < rows; i++){
vector<string> temp;
for(int j = 0; j < col; j++){
std::cin >> cell;
temp.push_back(cell);
}
game.push_back(temp);
}
vector<vector<string>> firstGen;
firstGen.insert(firstGen.end(),game.begin(),game.end());
if(numOfGen == 0){
std::cout << "numOfGen == 0" << std::endl;
for(int i = 0; i < rows; i++){
for(int j = 0; j < col; j++){
std::cout << game[i][j] << " ";
}
std::cout << std::endl;
}
}
for(int g = 0; g <= numOfGen; g++){
for(int i = 1; i < rows; i++){
for(int j = 1; j < col; j++){
gameOfLife(game, firstGen, i, j, rows, col);
}
}
if(g == numOfGen){
for(int i = 0; i < rows; i++){
for(int j = 0; j < col; j++){
std::cout << game[i][j] << " ";
}
std::cout << std::endl;
}
}
}
return 0;
}

Answer 1

Looks like firstGen never gets updated, so you're just computing the first generation over and over. So your output is probably correct for a single generation, but it's the same for any number of generations. Also, check the conditions on your main driver loop: with for(int g = 0; g <= numOfGen; g++) the loop executes numOfGen+1 times.