operators in classes
Author
Hi
i have a little problem with operator overloading in classes here:
in my class Vector i have this function:Vector Vector::operator* ( float f )
with this i can make statements such as
Vector a;
Vector b = a * 2;
but what please do i have to do if i want get a statement like b = 2 * a to work??
This only gives me an error that no global operator is defined that accepts ''class Vector''
So does anyone know how i have to define my function to get it to work?
Thanks for your help,
Burning_Ice
I''m a little bit rusty, because it''s been a while since I''ve done this, but I believe you define a global function that has both operands listed:
Vector operator*(float a, Vector v)
and you''ll be ok.
I could be wrong though. Like I said, it''s been a while since I''ve done it.
Vector operator*(float a, Vector v)
and you''ll be ok.
I could be wrong though. Like I said, it''s been a while since I''ve done it.
Something like this:
---- --- -- -
Blue programmer needs food badly. Blue programmer is about to die!
class Vector { /* data here */public: /* constructors, etc */ friend Vector operator*(float f, const Vector& v); friend Vector operator*(const Vector& v, float f);};/* somewhere outside of the class */Vector operator*(float f, const Vector& v){ Vector result; /* calculate value, store in result */ return result;}/* do same for other version of operator* */---- --- -- -
Blue programmer needs food badly. Blue programmer is about to die!
Make sure you''ve defined your copy constructor and assignment operator.
Vector::operator =(Vector &a, Vector &b)
and yes, you have to define a function that will accept two vector operands, and if you want to use it fora vector times an integer, you have to define a separate function as well
Vector::operator *(Vector &a, Vector &b);
Vector::operator *(Vector &a, int &b);
get it I hope? Operators that only need one parameter are operators like ++
DarkAgito
Vector::operator =(Vector &a, Vector &b)
and yes, you have to define a function that will accept two vector operands, and if you want to use it fora vector times an integer, you have to define a separate function as well
Vector::operator *(Vector &a, Vector &b);
Vector::operator *(Vector &a, int &b);
get it I hope? Operators that only need one parameter are operators like ++
DarkAgito
yes when you overload an operator and want it to work with a specific class, you need to declare it as a friend to the class, but not a member.
operators should be declared as member functions of the class when the class will be the left hand operator (like the assignment operator, which must be a member function). If the class is a right hand member and a different object is a left hand member, make the function a friend of the class. And make sure copy and assignment operators are defined too.
class X{ int y;public: X() : y(0) {} X(int i) : y(i) {} X(const X& other) : y(other.y) {} X& operator = (const X& other) { y=other.y; return *this; } bool operator == (const int right) { return y==right; } friend bool operator == (const int left, const X right); //...};bool operator == (const int left, const X right){ return left==right.y; } This topic is closed to new replies.
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