SamoK wrote:
Hy!
I'd like to know how can I use ref and out parameters in c++.
I'd like to send (from C#) to my C++.net function a variable by reference,
so I could change it in my c++.net function.
And all I find about this topic is about C#.
Managed C++ doesn't provide those keywords, which are C# features, not .NET
features. AFAIK, it isn't possible to write a C++ function that C# views as
having out parameters, but you can write a C++ function that C# views as
having ref parameters. For example:
// a1.cpp
#using <mscorlib.dll>
using namespace System;
public __gc struct X
{
int x;
X()
: x(2)
{
}
void f1(int __gc * x)
{
++*x;
}
static void f2(X __gc * __gc * p)
{
X* q = new X;
q->x = (*p)->x;
++q->x;
*p = q;
}
};
// a.cs
using System;
public class MyClass
{
static void Main()
{
X x = new X();
X x2 = x;
int i = 0;
Console.WriteLine("i = {0}", i);
x.f1(ref i);
Console.WriteLine("i = {0}", i);
Console.WriteLine("x RefEquals x2 == {0}",
Object.ReferenceEquals(x, x2));
Console.WriteLine("x.x = {0}", x.x);
Console.WriteLine("x2.x = {0}", x2.x);
X.f2(ref x);
Console.WriteLine("x RefEquals x2 == {0}",
Object.ReferenceEquals(x, x2));
Console.WriteLine("x.x = {0}", x.x);
Console.WriteLine("x2.x = {0}", x2.x);
}
}
C>cl -LD -clr -W3 a1.cpp
C>csc a.cs /r:a1.dll
C>a
i = 0
i = 1
x RefEquals x2 == True
x.x = 2
x2.x = 2
x RefEquals x2 == False
x.x = 3
x2.x = 2
--
Doug Harrison
Microsoft MVP - Visual C++
