declare 2nd array without size

Question

how can declare a 2nd or multidimensional array without first size in c++?

class numeric 
{
    public:
    int int_array_numbers[][];
    ...
};

Error message: declaration of 'int_array_numbers' as multidimensional array must have bounds for all dimensions except the first

Hope this link is helpful [enter link description here][1] [1]: http://stackoverflow.com/questions/5737905/why-c-c-allows-omission-of-leftmost-index-of-a-multidimensional-array-in-a-fun — Raj, Jun 25 '12 at 08:39

score 11 · Answer 1 · answered Jun 25 '12 at 08:32

11

You can't, C++ doesn't support VLA's (variable length arrays).

Use a std::vector<std::vector<int> > instead.

answered Jun 25 '12 at 08:32

Luchian Grigore

3

@AliN you don't want to or you can't? Because if you can but you just don't want to, you should just get over it. :) – Luchian Grigore Jun 25 '12 at 08:33
3

@AliN, since when vector isn't standard library? o.O – Griwes Jun 25 '12 at 08:34
1

std::vector is from the standard lib, as its name implies (std == standard) – Scharron Jun 25 '12 at 08:34

score 5 · Accepted Answer · edited Jun 25 '12 at 08:35

5

you can declare your class as template from two arguments something like this

template <int N, int M>
class numeric 
{
public:
     int int_array_numbers[N][M];
...
};

edited Jun 25 '12 at 08:35

Luchian Grigore

answered Jun 25 '12 at 08:35

zapredelom

In which case, `N` and `M` have to be compile time constants. But it wouldn't be hard to make them arguments to the constructor, with a `std::vector` member initialized to `N * M`, and an overloaded `[]` operator which did the right thing. – James Kanze Jun 25 '12 at 08:55

2 Answers2