On 11/28/2011 05:41 PM, David Currie wrote:
> I am a newbie to D. From (C++,Java,others...) background.
>
> In C++ I can say
>
> void f1(int& pInt)
> {
> pInt = 1;
> }
>
> which sets pInt(which is outside f1)
> because although pInt (at compile time) is a Value
> in reality it is passed by reference(address).
>
> Now
>
> void f2(int* pIntPtr)
> {
> *pIntPtr = 1;
> ++pIntPtr;
> *pInt = 2;
> }
> sets (the contents of) pInt to 1 (and the next immediate address to 2)
>
> All this is of course standard C++.
>
> How is this type of thing done in D
> (changing objects by passing by reference etc)?
Pointers are the same in D but needed far less than C++.
For parameter passing, the ref keyword can be used:
void f3(ref int pInt)
{
// ...
}
Also check out 'out' parameters:
void f4(out int pInt)
{
// ...
}
The difference from ref is the fact that out parameters are initialized
to .init of their type when entering the function. They are documented
here: http://d-programming-language.org/function.html
Additionally, you may find it surprising that classes are reference
types in D (unlike structs, which are value types as in C and C++). So
you don't need to use the ref keyword, as the class object would be
passed by reference as the class variable:
class C
{
// ...
}
void f5(C c) // <-- reference to the class object
{
// ...
}
Other reference types of D are dynamic arrays and associative arrays
(importantly, fixed-length arrays are value types!)
Ali
