Overloading Operator parameters [duplicate]

Question

I was wondering how many parameters can an overloaded operator take in C++?

I've seen operators take both one and two parameters, so I wanted to know if they can take both or just one, specifically for the - and << operators.

<< - No. That would be syntax error. - - yes, there is an unary minus operator. — Elazar
– Elazar, Commented Jun 7, 2015 at 23:49
.. Actually, Is it possible to overload operator associativity in C++? has a better answer: "Overloaded operators obey the rules for syntax specified in Clause 5." — Jongware
– Jongware, Commented Jun 7, 2015 at 23:55

Mureinik · Accepted Answer · 2015-06-07 23:54:15Z

1

The << always takes one parameter. E.g. with x << y, x would be the instance operator<<() is called from and y would be its parameter. Of course, you could overload the operator with different types of y, but always only one.

The - operator has two flavors, and is indeed overloaded with different number of arguments:

Unary (-x)
Binary (x - y)

answered Jun 7, 2015 at 23:54

Mureinik

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Karim O. · Accepted Answer · 2015-06-07 23:55:15Z

0

For the minus operator, it can only take one parameter like so:

object& operator-(const object &ref); //please note the syntax and use of const

For the << operator (called ostream), you overload it like so, it takes two parameters:

friend ostream& operator<<(ostream &str, const object &ref);

Hope that answers your question.

answered Jun 7, 2015 at 23:55

Karim O.

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