Topic: Reference operator similar usage in C#

[Spike Wilbury]

I know that in C# pointers can be use in unsafe code... i am confused here, this is what I am trying to do (i'm porting some C++ code to C#):

In C++ i can have a function like the one below:

static void angleMinLine (AcGePoint3d p1, AcGePoint3d p2, double& Ang, double& Angmin)
{
... here do something and change the values of Ang and Angmin
}

So, for example i can call the function angleMinLine(); like:

double Ang = 30.0;
double Angmin = 76.0;
angleMinLine(sp, ep, Ang, Angmin);

And the values of Ang and Angmin are modified.

How can i do the same in C# (do i place those variables as a part of the class instead?)

Thanks!
Luis.-

[Draftek]

Use the 'ref' keyword - from the help:

class RefExample
{
    static void Method(ref int i)
    {
        i = 44;
    }
    static void Main()
    {
        int val = 0;
        Method(ref val);
        // val is now 44
    }
}

[Keith™]

interesting question - I hadn't thought of doing that.

[Bryco]

I use ref a lot when I need 2 answers,
if (!Util.Get.getpoint("\nPick the leader start point:", ref P1)) return;
Here getpoint returns a bool describing success  and P1 returns the chosen point

[Spike Wilbury]

Thanks!, i was right in there... 10-4 now

Use the 'ref' keyword - from the help:

class RefExample
{
    static void Method(ref int i)
    {
        i = 44;
    }
    static void Main()
    {
        int val = 0;
        Method(ref val);
        // val is now 44
    }
}

[Spike Wilbury]

I use ref a lot when I need 2 answers,
if (!Util.Get.getpoint("\nPick the leader start point:", ref P1)) return;
Here getpoint returns a bool describing success  and P1 returns the chosen point

that it is ! thanks.

[sinc]

You may also want to use "out".  With "ref", the values should already exist before the method call, while with "out", the method creates new values.  The compiler will support this.

For example, this will cause the compiler to complain about "Use of unassigned variables" for both 'val1' and 'val2':

Code: [Select]

void test(ref T arg1, ref T arg2)
{
}

void myMethod()
{
    T val1, val2;
    // val1 and val2 should be created here to prevent error
    test(ref val1, ref val2);  //  <---- compiler error is for this line
}

On the other hand, this one will warn you that 'arg1' and 'arg2' "must be assigned before control leaves the method".

Code: [Select]

void test(out T arg1, out T arg2)  //  <---- compiler error is for this line
{
    // arg1 and arg2 should be created here to prevent error
}

void myMethod()
{
    T val1, val2;
    test(out val1, out val2);
}


[Spike Wilbury]

Thank you Sinc,

I already did a test like that.

I need to change some existing values inside of functions.


Luis.

[Draftek]

I use 'ref' and 'out' frequently and then have the method return a bool whether it worked or not.

[Kerry]

I use 'ref' and 'out' frequently and then have the method return a bool whether it worked or not.

ditto ...
and the  'out' keyword in the calling statement is sufficient documentation usually.