Pointers to pointers vs. normal pointers

Question

The purpose of a pointer is to save the address of a specific variable. Then the memory structure of following code should look like:

int a = 5;
int *b = &a;         


        

Answer 1

The type system of C requires this, if you want to get a correct warning and if you want the code to compile at all. With only one level of depth of pointers you wouldn't know if the pointer is pointing to a pointer or to an actual integer.

If you dereference a type int** you know the type you get is int* and similarly if you dereference int* the type is int. With your proposal the type would be ambiguous.

Taking from your example, it is impossible to know whether c points to a int or int*:

c = rand() % 2 == 0 ? &a : &b;

What type is c pointing to? The compiler doesn't know that, so this next line is impossible to perform:

*c;

In C all type information is lost after compiling, as every type is checked at compile-time and isn't needed anymore. Your proposal would actually waste memory and time as every pointer would have to have additional runtime information about the types contained in pointers.