2d array with new[]

[Ideswa]

I use a 2d array and I declare it like this:

double * table = new double[2][num];

the integer "num" is entered by the user. Dev-C++ gives errors:

functions.h:47: cannot convert `double (*)[((num - 1) + 1)]' to `double*' in
initialization

What is wrong?

[TheDan]

Well as far as I know, you can only make 1D arrays dynamically.

Since you know the size of one bit of it, why not just create an array of pointers like this:

double *table[2];

Then you just go through each element of the array and create a new double of length 'num':

for (int x = 0; x < 2; x++)
    table[x] = new double[num];

[laserlight]

Well, I suppose you could do something like this:

const int table_size = 2;
double* table[table_size];

for (int i = 0; i < table_size; ++i) {
	table[i] = new double[num];
}

// ...

for (int i = 0; i < table_size; ++i) {
	delete[] table[i];
}

Have you considered using vectors?

[Salem]

> double * table = new double[2][num];
You can only do multiple dimensions like this if all the minor dimentions are compile-time constants.

Eg.
double (*table)[2] = new double[num][2];

[Ideswa]

Thanks for the replies!

@laserlight:
I don't know how to use vectors yet

[Daved]

If you are learning C++, many would suggest learning vectors before C style arrays.