c++ - Cannot cast array to pointer

Question

I have the following source:

#include <iostream>
using namespace std;

void main(int j)
{
    char arr[10][10];
    char** ptr;
    ptr = arr;
}

when I compile it using VS2010 I get this error:

error : a value of type "char (*)[10]" cannot be assigned to an entity of type "char **"

I thought arrays in c++ were just pointers. So a char[][] could also be char**. What am I doing wrong?

Answer 1

Arrays aren't pointers.

An array decays to a pointer in most circumstances, but this isn't recursive. So a T[] decays to a T *, but a T[][] doesn't decay to a T**.

I suggest reading the whole of the C FAQ chapter on arrays and pointers; in particular, the section on 2D arrays and pointers-to-pointers.