Reading txt into 2D Array

[J Mac]

My assignment for class is to create a program like Life. In the program, we have to read a txt file into a 2D array that acts as the map for the game. The txt file looks like this...

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
O............................O
O............................O
O............................O
O..........XX................O
O..........XX................O
O............................O
O............................O
O............................O
O............................O
O............................O
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

...where 'O' are the boundaries, '.' are dead cells, and 'X' are live cells.

My code looks like...

{
	int rows=0, cols;
	in_file.open("text.txt");
	if (in_file)
	{
		getline(in_file, gstring, '\n');
	while(in_file)
		{	
			for (cols=0; cols<COLS_SIZE; cols++)
			{
				char  *ptr = &gstring[cols];
				array1[rows][cols]=*ptr;
			}
			getline(in_file, gstring, '\n');
			rows++;
		}
	}
}

My code compiles, but keeps giving me a "string subscript out of range" error within the program run time.