operator>>

What does it mean to have operator as a prefix to >>, or != or ==, or any of the other operands?

You mean things like:

Code:

---

bool operator==( const Obj& lhs, const Obj& rhs );

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It's defining a custom operator (i.e. it's a function).

Quote:

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Originally Posted by cpjust

You mean things like:

Code:

---

bool operator==( const Obj& lhs, const Obj& rhs );

---

It's defining a custom operator (i.e. it's a function).

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Why do you need custom operators?

So that you can do things like this:

Code:

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std::cout << "Hello World." << std::endl;

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or this:

Code:

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std::string str = std::string("Hello") + " World.";

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Generally, when defining operators for classes, try to stay true to the original meaning of the operator. (ie, '+' means 'add')

[QUOTE=Cactus_Hugger;775139]So that you can do things like this:

Code:

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std::cout << "Hello World." << std::endl;

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or this:

Code:

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std::string str = std::string("Hello") + " World.";

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So its like, you could assign them in a different way, or use operators in a different way for classes???

Just like Cactus_Hugger said, you usually need to overload certain operators of an object (e.g. the copy constructor / '=', or comparisons like <, ==, or >). So, if it's not overloaded, it won't do what you want it to do.

E.g. a class 'Matrix' to define a 3d matrix. If you haven't overloaded the 'equal to' operator and call this:

Code:

---

class Matrix
{
  private:
      float x;
      float y;
      float z;
...
}
Matrix a, b;
....
if (a == b)
{
...
}

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It would mostly returned a false because it wouldn't compare the values of the x, y, z. Now, if you do an operator overload like:

Code:

---

class Matrix
{
  private:
      float x;
      float y;
      float z;
  public:
      bool operator=(const Matrix &operand)
      {
            return ((this->x == operand->x) &&
                        (this->y == operand->y) &&
                        (this->z == operand->z) &&);
      }
}

---

It would compare between two matrices just like you wanted it to.

Quote:

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Originally Posted by g4j31a5

Just like Cactus_Hugger said, you usually need to overload certain operators of an object (e.g. the copy constructor / '=', or comparisons like <, ==, or >). So, if it's not overloaded, it won't do what you want it to do.

E.g. a class 'Matrix' to define a 3d matrix. If you haven't overloaded the 'equal to' operator and call this:

Code:

---

class Matrix
{
  private:
      float x;
      float y;
      float z;
...
}
Matrix a, b;
....
if (a == b)
{
...
}

---

It would mostly returned a false because it wouldn't compare the values of the x, y, z. Now, if you do an operator overload like:

Code:

---

class Matrix
{
  private:
      float x;
      float y;
      float z;
  public:
      bool operator=(const Matrix &operand)
      {
            return ((this->x == operand->x) &&
                        (this->y == operand->y) &&
                        (this->z == operand->z) &&);
      }
}

---

It would compare between two matrices just like you wanted it to.

---

Cool.. But wouldn't you need bool operator==(const Matrix &operand) instead?

Quote:

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Originally Posted by bobbelPoP

Cool.. But wouldn't you need bool operator==(const Matrix &operand) instead?

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Oh right. Sorry, it's 1 hour to go before the end of the workday (yay!). So my head is kinda messed up right now. :p

Quote:

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Originally Posted by g4j31a5

Oh right. Sorry, it's 1 hour to go before the end of the workday (yay!). So my head is kinda messed up right now. :p

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Ah, well thanks anyway, but can it be anything besides &operand? I dont know what &operand is?

The type is const Matrix& (this is why I prefer to type const Matrix& something and not const Matrix &something).
Essentially, it takes a (const) reference (the &) to an object of type Matrix.
Const reference means it cannot modify the object.

But it can be anything you like. So long as it makes sense.