Yes, the code is standard conforming. The + triggers a conversion to a plain old function pointer for the lambda. What happens is this: The compiler sees the first lambda ([]{}) and generates a closure object according to §5.1.2. As the lambda is a non-capturing lambda, the following applies: 5.1.2 Lambda expressions [expr.prim.lambda] 6 The … Read more
If you define your operator overloaded function as member function, then the compiler translates expressions like s1 + s2 into s1.operator+(s2). That means, the operator overloaded member function gets invoked on the first operand. That is how member functions work! But what if the first operand is not a class? There’s a major problem if … Read more
You can overload operator[] to return an object on which you can use operator[] again to get a result. class ArrayOfArrays { public: ArrayOfArrays() { _arrayofarrays = new int*[10]; for(int i = 0; i < 10; ++i) _arrayofarrays[i] = new int[10]; } class Proxy { public: Proxy(int* _array) : _array(_array) { } int operator[](int index) … Read more
No, Java doesn’t support user-defined operator overloading. The only aspect of Java which comes close to “custom” operator overloading is the handling of + for strings, which either results in compile-time concatenation of constants or execution-time concatenation using StringBuilder/StringBuffer. You can’t define your own operators which act in the same way though. For a Java-like … Read more
This is one of those frequently asked questions that have different approaches that are similar but not really the same. The three approaches differ in who you are declaring to be a friend of your function –and then on how you implement it. The extrovert Declare all instantiations of the template as friends. This is … Read more
Common operators to overload Most of the work in overloading operators is boiler-plate code. That is little wonder, since operators are merely syntactic sugar, their actual work could be done by (and often is forwarded to) plain functions. But it is important that you get this boiler-plate code right. If you fail, either your operator’s … Read more
Most types in .NET derive from the type System.Object, simply called object in C#. (E.g. interfaces don’t, however their implementations do.) System.Object declares the methods Equals and GetHashCode as well as other members. (Note: The case matters in C#). The types you create automatically inherit these methods. The task of Equals is to compare an … Read more
I am legitimately intrigued why both the topic you linked, and https://arne-mertz.de/2015/01/operator-overloading-common-practice/ or many others never talk about a left operand from another type than ostream. Because it does not really matter. What works for std::ostream works similar for other types. Sorry, but its a bit like getting an example of overloading operator+ for a … Read more