How to access 1 element in 2D dynamic array in C++

Question

I'm new to C++, and I've been trying to figure out how to access just 1 element in a 2D array that I've dynamically allocated like so:

char** array;
array = new char*[3];
for(int i = 0; i < 3; i++) {
    array[i] = new char [3];
}

I've been trying to access it like this:

cout<< array[0][0];

Whenever I try to do this, nothing prints out and the program segfaults. How should I fix it so that it prints? Thank you for your time!

It seems the above code shouldn't compile to start with: `new char*[3]` returns a `char**` but `*array` yields a `char*` (or my brain is fried for some reason...). — Dietmar Kühl, Dec 25 '16 at 22:52
@DietmarKühl your brain isn't fried, it doesn't compile on [IDEOne](http://ideone.com/yU11bj) — UnholySheep, Dec 25 '16 at 22:55
Did you place any value in `array[0][0]`? If not, what did you expect to print? — StoryTeller - Unslander Monica, Dec 25 '16 at 23:06
I'm positive the array is filled. I want it to print the letter "a". — prestococo, Dec 25 '16 at 23:10
I'm not so positive. Post a [minimal and complete example](http://stackoverflow.com/help/mcve), not independent code lines. — StoryTeller - Unslander Monica, Dec 25 '16 at 23:11
Actually, I figured out my problem... I made a mistake dynamically allocating my array. Funny how I wasn't able to see that sooner. Sorry for all the trouble and thank you! — prestococo, Dec 25 '16 at 23:36

score 0 · Accepted Answer · edited May 23 '17 at 12:00

If you're looking to create a 2D array you should take a look at this Stack Overflow post here. It has a nice image to explain how 2D memory is laid out and how to properly create the array. Remember, when you create dynamic memory using new you need to delete the memory manually with delete[]. The second response gives a code example of how to delete the 2D array. Once you have your array you can access it by cout << array[x][y], where x and y are your row and column indices. I'd focus on properly creating the 2D array and understanding that first.

How to access 1 element in 2D dynamic array in C++

1 Answers1