CODEWITHSUNDEEP
.netobjectc++-climsdn
Rohit Vipin Mathews
Rohit Vipin Mathews

Reputation: 11787

why is the ^ operator used after Point in the following code about Object Class

This is an Example from MSDN about Object Class in .NET FrameWork. 

using namespace System;

// The Point class is derived from System.Object.
ref class Point
{
public:
    int x;
public:
    int y;

public:
    Point(int x, int y)
    {
        this->x = x;
        this->y = y;
    }

public:
    virtual bool Equals(Object^ obj) override
    {
        // If this and obj do not refer to the same type,
        // then they are not equal.
        if (obj->GetType() != this->GetType())
        {
            return false;
        }

        // Return true if  x and y fields match.
        Point^ other = (Point^) obj;
        return (this->x == other->x) && (this->y == other->y);
    }

    // Return the XOR of the x and y fields.
public:
    virtual int GetHashCode() override 
    {
        return x ^ y;
    }

    // Return the point's value as a string.
public:
    virtual String^ ToString() override 
    {
        return String::Format("({0}, {1})", x, y);
    }

    // Return a copy of this point object by making a simple
    // field copy.
public:
    Point^ Copy()
    {
        return (Point^) this->MemberwiseClone();
    }
};

int main()
{
    // Construct a Point object.
    Point^ p1 = gcnew Point(1, 2);

    // Make another Point object that is a copy of the first.
    Point^ p2 = p1->Copy();

    // Make another variable that references the first
    // Point object.
    Point^ p3 = p1;

    // The line below displays false because p1 and 
    // p2 refer to two different objects.
    Console::WriteLine(
        Object::ReferenceEquals(p1, p2));

    // The line below displays true because p1 and p2 refer
    // to two different objects that have the same value.
    Console::WriteLine(Object::Equals(p1, p2));

    // The line below displays true because p1 and 
    // p3 refer to one object.
    Console::WriteLine(Object::ReferenceEquals(p1, p3));

    // The line below displays: p1's value is: (1, 2)
    Console::WriteLine("p1's value is: {0}", p1->ToString());
}

// This code produces the following output.
//
// False
// True
// True
// p1's value is: (1, 2)

What i dont understand is why is the ^ operator used after Point. Someone Kindly Explain.

Upvotes: 3

Views: 161

Answers (3)

Dominik Grabiec
Dominik Grabiec

Reputation: 10655

This is C++/CLI, formerly known as Managed C++ code, where you can mix standard C++ and use .Net libraries as well.

The ^ hat operator declares the variable to be a Garbage Collected Handle as opposed to a standard C style pointer * or a C++ reference &.

Upvotes: 1

Naveen
Naveen

Reputation: 73443

The ^ operator is the managed C++ way of creating handles. See here

Upvotes: 1

porges
porges

Reputation: 30580

This is C++/CLI, not just plain C++.

The ^ is basically the .NET equivalent of ordinary *, but it defines a handle, rather than a pointer. Handles can be null, just like pointers.

So Point^ is a handle to an instance of the Point class.

You can read more about it on MSDN.

Upvotes: 3

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