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I have a question about a pointer to 2d array. If an array is something like
int a[2][3]; then, is this a pointer to array a?
int (*p)[3] = a; If this is correct, I am wondering what does [3] mean from int(*p)[3]?
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Pointers and two dimensional Arrays: In a two dimensional array, we can access each element by using two subscripts, where first subscript represents the row number and second subscript represents the column number. The elements of 2-D array can be accessed with the help of pointer notation also.
Get the element => *( (int *)aiData + offset ); calculate offset => offset = (1 * coloumb_number)+ 2); Add offset in array base address => (int *)aiData + offset; //here typecast with int pointer because aiData is an array of integer Get the element => *( (int *)aiData + offset );
When we allocate memory to a variable, pointer points to the address of the variable. Unary operator ( * ) is used to declare a variable and it returns the address of the allocated memory. Pointers to an array points the address of memory block of an array variable.
So the upshot of that is yes, you can use the [] subscript operator on a pointer expression as well as an array expression. Pointers don't have to be represented as integers - on some older segmented architectures, they were represented as a pair of values (page number and offset).
int a[2][3]; a is read as an array 2 of array 3 of int which is simply an array of arrays. When you write,
int (*p)[3] = a;
It declares p as a pointer to the first element which is an array. So, p points to the array of 3 ints which is a element of array of arrays.
Consider this example:
int a[2][3] +----+----+----+----+----+----+ | | | | | | | +----+----+----+----+----+----+ \_____________/ | | | p int (*p)[3] Here, p is your pointer which points to the array of 3 ints which is an element of array of arrays.
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