Derived data types

In this section, we're going to observe D's take on pointers, arrays, strings, and associative arrays. Much of what we'll cover here is very different from other C-family languages.

Pointers

As in other languages that support them, pointers in D are special variables intended to hold memory addresses. Take a moment to compile and run the following:

int* p;
writeln("p's value is ", p);
writeln("p's type is ", typeid(p));
writeln("p's size is ", p.sizeof);	

First, look at the declaration. It should look very familiar to many C-family programmers. All pointer declarations are default initialized to null, so here the first call to writeln prints "null" as the value. The type of p printed in the second writeln is int*. The last line will print 4 in 32-bit and 8 in 64-bit.

So far so good. Now look at the following line and guess what type b is:

int* a, b;

No, b is not an int, it is an int*. The equivalent C or C++ code would look like this:

int *x, *y;

In D, x would be interpreted as...