how to define a bidimensional dynamic array as a global variable?

[lumumba401]

Hello everybody,

i am asking about how to define a bidimensional dynamic array as a global variable to use as incoming variable in a function

Let us see , for example in a part of a programm my problem:

#include<iostream>
...
using namespace std;

float a[10][10];//in this place i wish define a bidimenional dynamic array agian: how to do it?
...
//follow the function

float suma(int k, float a[][10])
{
float s=0;
for (int i=1;i<k;i++)
for (int j =1;j<k;j++)
s=s+a[i][j];
return (s);
}

int main()
{
...
suma(k,a);
...
}

But instead defining an static bidimensional array a[10][10], to use after as an incoming variable in a function, i wish to define it as dynamic array(to work with a huge array, for example(a[500][500]) )

would you like to help me?
Bye .
Miguel.

[arnaudk]

First of all, it's usually not a good idea to use global variables. Then, before you start using 2D dynamic arrays, you should understand 1D dynamic arrays; you can then implement a 2D array as an array of an array. If performance is a real issue then use a proper matrix class like the one provided in boost or blitz++ (C++) or GSL (C/C++), there are many others.

Also, if your problem is simply that you wish to work with large arrays then this has nothing to do with dynamic arrays. Just declare a large static array.