• David Currie (20/20) Nov 28 2011 I am a newbie to D. From (C++,Java,others...) background.
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (30/50) Nov 27 2011 Pointers are the same in D but needed far less than C++.
• Andrej Mitrovic (14/14) Nov 27 2011 Use ref:
• Andrej Mitrovic (1/1) Nov 27 2011 Damn you Ali!! xD
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (3/4) Nov 27 2011 No no: Both of us are waiting for someone to correct us. :)
• Graham Fawcett (4/31) Nov 28 2011 Try

David Currie <curriedr iinet.net.au> writes:

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)?

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

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

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

Use ref:

void f1(ref int val)
{
    val = 1;
}

Another one is 'out', which initializes the type with it's .init value
on function entry:

void foo(out int val) {}

This is (I believe) equivalent to the following:

void foo(ref int val)
{
    val = int.init;
    // your code here..
}

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

Damn you Ali!! xD

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 11/27/2011 11:15 PM, Andrej Mitrovic wrote:
 Damn you Ali!! xD

No no: Both of us are waiting for someone to correct us. :)

Ali

Graham Fawcett <fawcett uwindsor.ca> writes:

On Mon, 28 Nov 2011 17:41:08 -0800, 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)?

Try 

void f1(ref int pInt)

Graham