returning d array from function

[abdulsamad]

can any1 tell me how to return 2d array from a nested functions......


i am doing it like that i have two classes........ ...

Game{
private:
int array[6][6];
public:
int** fillArray()
{
return array;
}

};
Graphics
{
private:
Game play;
int** fillArray()
{
int **array=play.fi llArray();
return array;
}

};
void main()
{
Graphics gr
int **arr= gr.fillaArray() ;
}


If there is some way to do this kindly tell me i am in extreme trouble ....there is some trouble in this code so kindly tell me


regards Abdul Samad

[weaknessforcats]

You'd better read this first:

First, there are only one-dimensional arrays in C or C++. The number of elements in put between brackets:
[code=c]
int array[5];
[/code]

That is an array of 5 elements each of which is an int.

[code=c]
int array[];
[/code]

won't compile. You need to declare the number of elements.

Second, this array:
[code=c]
int array[5][10];
[/code]

is still an array of 5 elements. Each element is an array of 10 int.

[code=c]
int array[5][10][15];
[/code]

is still an array of 5 elements. Each element is an array of 10 elements where each element is an array of 15 int.


[code=c]
int array[][10];
[/code]

won't compile. You need to declare the number of elements.

Third, the name of an array is the address of element 0
[code=c]
int array[5];
[/code]

Here array is the address of array[0]. Since array[0] is an int, array is the address of an int. You can assign the name array to an int*.

[code=c]
int array[5][10];
[/code]

Here array is the address of array[0]. Since array[0] is an array of 10 int, array is the address of an array of 10 int. You can assign the name array to a pointer to an array of 10 int:
[code=c]
int array[5][10];

int (*ptr)[10] = array;
[/code]

Fourth, when the number of elements is not known at compile time, you create the array dynamically:

[code=c]
int* array = new int[value];
int (*ptr)[10] = new int[value][10];
int (*ptr)[10][15] = new int[value][10][15];
[/code]

In each case value is the number of elements. Any other brackets only describe the elements.

Using an int** for an array of arrays is incorrect and produces wrong answers using pointer arithmetic. The compiler knows this so it won't compile this code:

[code=c]
int** ptr = new int[value][10]; //ERROR
[/code]

new returns the address of an array of 10 int and that isn't the same as an int**.

Likewise:
[code=c]
int*** ptr = new int[value][10][15]; //ERROR
[/code]

new returns the address of an array of 10 elements where each element is an array of 15 int and that isn't the same as an int***.

With the above in mind this array:
[code=cpp]
int array[10] = {0,1,2,3,4,5,6, 7,8,9};
[/code]
has a memory layout of

0 1 2 3 4 5 6 7 8 9

Wheras this array:
[code=cpp]
int array[5][2] = {0,1,2,3,4,5,6, 7,8,9};
[/code]
has a memory layout of

0 1 2 3 4 5 6 7 8 9

Kinda the same, right?

So if your disc file contains

0 1 2 3 4 5 6 7 8 9

Does it make a difference wheher you read into a one-dimensional array or a two-dimensional array? No.

Therefore, when you do your read use the address of array[0][0] and read as though you have a
one-dimensional array and the values will be in the correct locations.

and then post again if you still have questions.

[abdulsamad]

then should i return it like that


int* fillArray()
{
return array; // where array is a 2d array
}


void main()
{
int array[6][6];
array=fillArray ();
}


if not kindly send me the code which will return the 2D array

[weaknessforcats]

A 2D array of int cannot be returned as an int*.

I have just added an article on arrays in the C/C++ HowTos forum and toward the end the article talks about returning arrays from a function.

Have a look: http://www.thescripts.com/forum/thread772412.html.