multi dimensional array

[newbie30]

Say we have this:
int array[2]={1,2};
int *ptr = array;
cout<<ptr[1];


Now if we have this
int array[2][2];

//pretend it contains values, save me writing code:0

how do i assign a pointer to this multi dimensional array?

Thanks

[laserlight]

If you want a pointer to an array of 2 elements:

int (*p)[2] = array;

[newbie30]

I want a pointer to the multi dimensional array.

Was thinking i need to use a double pointer for it. But just cant seem to implement it.

[laserlight]

I want a pointer to the multi dimensional array.

Why would you want that? You more likely want either a pointer to an array of 2 elements so that you can iterate over the elements of the 2D array, or a pointer to an int so that you can directly iterate over the ints in the 2D array.

[newbie30]

With a one dimensional array we can have a pointer to it, correct?

but with multidimensional you cant?

I was just playing around with code and i was just trying to print the elements of the multidimensional array using a pointer, the same way you can with a one dimensional array.

[laserlight]

With a one dimensional array we can have a pointer to it, correct?

Yes, e.g.,

int numbers[2] = {1, 2};
int (*p)[2] = &numbers;

but with multidimensional you cant?

No, you also can:

int numbers[2][2] = {{1, 2}, {3, 4}};
int (*p)[2][2] = &numbers;

Notice that I am taking you literally here: we are talking about pointer to arrays, not pointers to the first elements of arrays, hence I write &numbers on the right hand side of the assignment rather than just numbers to get the address of the array.

I was just playing around with code and i was just trying to print the elements of the multidimensional array using a pointer, the same way you can with a one dimensional array.

You can try:

#include <iostream>
#include <cstddef>

int main()
{
    int numbers[2][2] = {{1, 2}, {3, 4}};
    const std::size_t total_size = sizeof(numbers) / sizeof(numbers[0][0]);

    for (int* p = &numbers[0][0], *end = &numbers[0][0] + total_size; p != end; ++p)
    {
        std::cout << *p << ' ';
    }
    std::cout << std::endl;
}

This would be the "pointer to an int so that you can directly iterate over the ints in the 2D array" idea.

[Abhishek Chauhan]

int myArray={{0.1} , {2,3} }
Int (*ptr) [2][2] = &myArray;

[newbie30]

int(*ptr)[2][2] = &array;


I know we are pointing to the address of the array but what does the first part actually say:

ie this part int(*ptr)[2][2]


Thanks

[laserlight]

I know we are pointing to the address of the array but what does the first part actually say:

ie this part int(*ptr)[2][2]

That means "a pointer named ptr to an array of two arrays of two ints".

[newbie30]

but why the brackets around the pointer?

[laserlight]

but why the brackets around the pointer?

Ugly syntax inherited from C

Without the parentheses you end up with an array of 2 arrays of 2 int pointers.

[newbie30]

thanks the perfect answer for me.