Pass parameters by ref from c# to managed c++

[Pravin]

I have a function as follows in managed c++.

public foo( object *objectValue)
{
// pseudo code below, as I don't have exact code at this very moment.
if( type of objectValue is int)
{
objectValue = objectValue * 2;
}
elseif(type of objectValue is short)
{
objectValue = objectValue * 3;
}
// This function does some more processing after this.
}

I wish to call above function from C#.

To say it briefly, from C# I wish to pass 'int' and 'short' type of objects
to a function in managed c++. Managed c++ code will alter the value. The
changed value should be available to me in C# code.

The problem: In C# if I call the above as:
int i = 10;
foo(ref i);
The above code gives me compilation error. If I do boxing, unboxing in c#
code to pass parameter, then the changed value is not reflected back in C#
function.

I request to please guide, how to achieve it? Thanks.

--
Regards,
Pravin Joshi

[Peter Q]

Re: Pass parameters by ref from c# to managed c++

Your C++ code requires a pointer argument, 'ref' aren't exactly the same a
pointer.

You should try this:

unsafe public integerManipula tion()
{
int i = 10;
foo(&i);
}

of course, turn on the unsafe option in ur compiler options


"Pravin" <expertco@vsnl. com> wrote in message
news:e8UVUtfgDH A.3968@tk2msftn gp13.phx.gbl...[color=blue]
> I have a function as follows in managed c++.
>
> public foo( object *objectValue)
> {
> // pseudo code below, as I don't have exact code at this very moment.
> if( type of objectValue is int)
> {
> objectValue = objectValue * 2;
> }
> elseif(type of objectValue is short)
> {
> objectValue = objectValue * 3;
> }
> // This function does some more processing after this.
> }
>
> I wish to call above function from C#.
>
> To say it briefly, from C# I wish to pass 'int' and 'short' type of[/color]
objects[color=blue]
> to a function in managed c++. Managed c++ code will alter the value. The
> changed value should be available to me in C# code.
>
> The problem: In C# if I call the above as:
> int i = 10;
> foo(ref i);
> The above code gives me compilation error. If I do boxing, unboxing in c#
> code to pass parameter, then the changed value is not reflected back in C#
> function.
>
> I request to please guide, how to achieve it? Thanks.
>
> --
> Regards,
> Pravin Joshi
>
>
>[/color]

[Willy Denoyette [MVP]]

Re: Pass parameters by ref from c# to managed c++

Should be:
MC++:

.....
public:
foo( Object **objectValue) {
*objectValue = ....
....
}

C# :
foo(ref i);

Willy.


"Pravin" <expertco@vsnl. com> wrote in message news:e8UVUtfgDH A.3968@tk2msftn gp13.phx.gbl...[color=blue]
> I have a function as follows in managed c++.
>
> public foo( object *objectValue)
> {
> // pseudo code below, as I don't have exact code at this very moment.
> if( type of objectValue is int)
> {
> objectValue = objectValue * 2;
> }
> elseif(type of objectValue is short)
> {
> objectValue = objectValue * 3;
> }
> // This function does some more processing after this.
> }
>
> I wish to call above function from C#.
>
> To say it briefly, from C# I wish to pass 'int' and 'short' type of objects
> to a function in managed c++. Managed c++ code will alter the value. The
> changed value should be available to me in C# code.
>
> The problem: In C# if I call the above as:
> int i = 10;
> foo(ref i);
> The above code gives me compilation error. If I do boxing, unboxing in c#
> code to pass parameter, then the changed value is not reflected back in C#
> function.
>
> I request to please guide, how to achieve it? Thanks.
>
> --
> Regards,
> Pravin Joshi
>
>
>[/color]

[Willy Denoyette [MVP]]

Re: Pass parameters by ref from c# to managed c++

Should be:
MC++:

.....
public:
foo( Object **objectValue) {
*objectValue = ....
....
}

C# :
foo(ref i);

Willy.


"Pravin" <expertco@vsnl. com> wrote in message news:e8UVUtfgDH A.3968@tk2msftn gp13.phx.gbl...[color=blue]
> I have a function as follows in managed c++.
>
> public foo( object *objectValue)
> {
> // pseudo code below, as I don't have exact code at this very moment.
> if( type of objectValue is int)
> {
> objectValue = objectValue * 2;
> }
> elseif(type of objectValue is short)
> {
> objectValue = objectValue * 3;
> }
> // This function does some more processing after this.
> }
>
> I wish to call above function from C#.
>
> To say it briefly, from C# I wish to pass 'int' and 'short' type of objects
> to a function in managed c++. Managed c++ code will alter the value. The
> changed value should be available to me in C# code.
>
> The problem: In C# if I call the above as:
> int i = 10;
> foo(ref i);
> The above code gives me compilation error. If I do boxing, unboxing in c#
> code to pass parameter, then the changed value is not reflected back in C#
> function.
>
> I request to please guide, how to achieve it? Thanks.
>
> --
> Regards,
> Pravin Joshi
>
>
>[/color]