Overloading arithmetic operators as member funtions
Help! I was studying operator overloading these days. I was able to overload +, -, * and / for a complex number class I wrote as friend and non-member functions, but failed miserably at overloading them as member functions. The code can be seen below.
I'm using MS Visual C++ express 2012. Error codes are in the 2nd post. The C2248 error seemed to be especially peculiar: how come a class type cannot access the private data members? This is not making sense at all!
I'm using MS Visual C++ express 2012. Error codes are in the 2nd post. The C2248 error seemed to be especially peculiar: how come a class type cannot access the private data members? This is not making sense at all!
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the first thing you should do is learn more about classes, and const correctness with classes.
Look up what the
Furthermore, it is improper to declare a new instance of a class within the class when modifying the class. Operators are mean to manipulate an instance of a class, not another instance.
here's an example:
class myclass{
public:
//......
myclass& operator=(const myclass& m)
{
this->member = myclass.member;
return *this;
}
myclass& operator+(const unsigned int& i)
{
this->member += i;
return *this;
}
//....
};
when you perform the following operation:
it is the same as:
if
Since I am doing this correctly, I could even do somthing like this:
if((c + 1)[5] == "an element")
{
cout<< c[5]<< endl;
}
Look up what the
this pointer is, it makes it easier for you to call member functions of a class with reference to the 'current' instance of the object (it's also probably easier).Furthermore, it is improper to declare a new instance of a class within the class when modifying the class. Operators are mean to manipulate an instance of a class, not another instance.
here's an example:
public:
//......
myclass& operator=(const myclass& m)
{
this->member = myclass.member;
return *this;
}
myclass& operator+(const unsigned int& i)
{
this->member += i;
return *this;
}
//....
};
when you perform the following operation:
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it is the same as:
c.operator=(c.operator+(1));if
.operator+(const unsigned int&) doesn't return a correct value (in this case, it is its self, which makes it redundant, but for your benefit...) it will throw a slew of errors like the onse you see.if((c + 1)[5] == "an element")
{
cout<< c[5]<< endl;
}
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Mr. IWishIKnew,
I had tried this pointer.
This is what I got:
This drove me nuts. The function is definitely non-static!
I had tried this pointer.
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This is what I got:
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This drove me nuts. The function is definitely non-static!
Last edited on
remove the const at the beginning of the function dec and make it return by address.
closed account (D80DSL3A)
And resolve the scope where defining the functions:
Not
but
Not
ComplexNumber operator +(const ComplexNumber& amount)but
ComplexNumber ComplexNumber::operator +(const ComplexNumber& amount)
> it is improper to declare a new instance of a class within the class when modifying the class.
If you need to create another object, create it.
You do not modify classes, you modify objects.
¡No! ¡¿How dare you to modify the object?! That's counter intuitive
> make it return by address.
Do not return an address to a temporary.
@OP: you are defining global functions. To define member functions do as fun2code shows.
If you want to observe const-correctness the prototype should be
If you need to create another object, create it.
You do not modify classes, you modify objects.
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¡No! ¡¿How dare you to modify the object?! That's counter intuitive
c = a+b; ¿why do you think is a good idea for `a' to change?> make it return by address.
Do not return an address to a temporary.
@OP: you are defining global functions. To define member functions do as fun2code shows.
If you want to observe const-correctness the prototype should be
const ComplexNumber operator /(const ComplexNumber& amount) const;
Last edited on
ah, yes. That makes more sense. Sorry, I have been studying the Qt libraries lately, it's been mind-numbing.
you only want to have the operators self-modify for operators ++, +=, -=, etc...
Thanks ne for correcting me.
you only want to have the operators self-modify for operators ++, +=, -=, etc...
Thanks ne for correcting me.
Last edited on
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