operator-overloading

问题 say I want to overload an operator (lets say + for now) for some class I've created, class A (object): #code here and then: a = A() b = A() what would I do to define: c = a + b or something along those lines? (note: this question is purely theoretical I will likely use this at some time, just not currently (unless its really easy and I really need a use for it)) (p.s. if it is possible to do this for other things such as and , or , not , str , e.t.c.) 回答1: Since A is the first operand of the

问题 I have extended the C++ 11 std::array , it is working file, but when I try to overload the operator[] , I got this error: error: lvalue required as left operand of assignment array[0] = 911; ^~~ Is it possible to implement the operator[] adding bound checking for the std::array type? This is the code: #include <array> #include <cassert> #include <iostream> template <unsigned int array_size, typename array_datatype=long int> struct Array : public std::array<array_datatype, array_size> { Array(

问题 TLDR: See the last paragraph. I have an operator& defined for several template classes like so: template <typename T> struct Class { Class(T const &t) { } }; template <typename T_Lhs, typename T_Rhs> struct ClassAnd { ClassAnd(T_Lhs const &lhs, T_Rhs const &rhs) { } }; template <typename T, typename T_Rhs> ClassAnd<Class<T>, T_Rhs> operator&(Class<T> const &lhs, T_Rhs const &rhs) { return ClassAnd<Class<T>, T_Rhs>(lhs, rhs); } template <typename T0, typename T1, typename T_Rhs> ClassAnd

问题 While playing with this answer by user GMan I crafted the following snippet (compiled with Visual C++ 9): class Class { public: operator void() {} }; Class object; static_cast<void>( object ); (void)object; object.operator void(); after stepping over with the debugger I found out that casting to void doesn't invoke Class::operator void() , only the third invokation (with explicitly invoking the operator) actually invokes the operator, the two casts just do nothing. Why is the operator void

问题 I know I can answer this question easily for myself by generatin the code and see if it compiles. But since I couldn't find a similar question, I thought it's knowledge worth sharing. Say I am overloading the + operator for MyClass. Can I overload it multiple times. Different overload for different types. Like this: class MyClass{ ... inline const MyClass operator+(const MyClass &addend) const { cout<<"Adding MyClass+MyClass"<<endl; ...//Code for adding MyClass with MyClass } inline const

问题 I read in http://en.cppreference.com/w/cpp/language/operators: The boolean logic operators, operator && and operator || Unlike the built-in versions, the overloads do not sequence their left operand before the right one, and (until C++17) cannot implement short-circuit evaluation. (My emphasis). Couldn't find any resource or code example for C++17 supporting short-circuit for operator&& and operator||. Is it related to C++17 parameter pack fold expression? tried to play with it but couldn't

问题 I read in http://en.cppreference.com/w/cpp/language/operators: The boolean logic operators, operator && and operator || Unlike the built-in versions, the overloads do not sequence their left operand before the right one, and (until C++17) cannot implement short-circuit evaluation. (My emphasis). Couldn't find any resource or code example for C++17 supporting short-circuit for operator&& and operator||. Is it related to C++17 parameter pack fold expression? tried to play with it but couldn't

问题 I've written an operator<< for my templated class: template<class T> std::ostream& operator<<(std::ostream &strm, const MyClass<T> &obj) and when I write cout << myClassInstance << endl; this compiles and runs, but my Eclipse CDT says: Invalid overload of 'endl' Why does it tell me that? (I use Eclipse CDT Kepler on Win7 64bit with Cygwin gcc) 回答1: This is indeed a bug with Eclipse CDT (more specifically Eclipse's Code Analysis tool CODAN). There is bug report and it has been fixed and should

问题 I need to overload some operators when called using Double types. To achieve this, I'm creating a class MyDouble, which inherits from Double. MyDouble looks somewhat like this class MyDouble : Double { Double value; // operator overloads go here } I want to abstract away the value property from the user so that it is usable just as a Double. Basically I want the user to be able to do this: MyDouble a = 5; //a.value gets assigned 5 Console.WriteLine(a); //prints a.value I don't want the user

问题 I need to overload some operators when called using Double types. To achieve this, I'm creating a class MyDouble, which inherits from Double. MyDouble looks somewhat like this class MyDouble : Double { Double value; // operator overloads go here } I want to abstract away the value property from the user so that it is usable just as a Double. Basically I want the user to be able to do this: MyDouble a = 5; //a.value gets assigned 5 Console.WriteLine(a); //prints a.value I don't want the user