default-constructor

I have a class MyClass in which I need to create a std::array of std::vector in the default constructor. However, this class has a data member which is a reference (of type Something ) which also needs to be initialized in the constructor and I cannot do this in a default constructor. How should I solve this? class MyClass{ public: MyClass(); //Cannot instantiate s?? MyClass(Something& s); Something& s; } MyClass array[10]; // MyClass needs a default constructor but a default // constructor won't be able to initialize s A class with a reference member needs to set the reference in its

I'm trying to understand how the compiler's default constructor works. I made this example: #include <iostream> class Base { public: int number; }; class Test1 : public Base { }; class Test2 { public: Base base; }; int main() { Test1 test1; Test2 test2; std::cout<<test1.number<<std::endl; std::cout<<test2.base.number<<std::endl; } The output of this test program is, for test1 0 , and for test2 is a uninitialized (random) number. Now my question is: why in the first case ( test1 ) the compiler's default constructor initialize number to 0 but for test2 it doesn't? Edit : According to answers

I'm targeting .NET 3.5 SP1 and I'm using CommentChecker to validate my XML documentation, everything works OK until I get to a class like this: /// <summary> /// documentation /// </summary> public sealed class MyClass { /// <summary> /// documentation /// </summary> public void Method() { } } In the example above, as I understand, the compiler generates a default constructor for my class. The problem with this is that CommentChecker generates warnings telling me that the constructor is missing the comments. I tried to modify the program to detect this special case and ignore it but I'm stuck,

Consider the code: #include <atomic> #include <iostream> struct stru { int a{}; int b{}; }; int main() { std::atomic<stru> as; auto s = as.load(); std::cout << s.a << ' ' << s.b << std::endl; } Note that although stru has default member initializer, it still qualifies as an aggregate type since C++14. std::atomic has a trivial default constructor. According to the standard, should the members of as be initialized to zero? clang 6.0.0 doesn't do this (see here ), while gcc 7.2.0 seems so (see here ). Strictly speaking, I think both compilers are right, in that your program exhibits undefined

I have a user control without a parameterless constructor; let's call it WithoutDefaultConstructor . I want to insert a WithoutDefaultConstructor called myControl into the XAML code of another control (which is called MainWindow ). However, I get this compiler error: The type 'WithoutDefaultConstructor' cannot have a Name attribute. Value types and types without a default constructor can be used as items within a ResourceDictionary. How do I fix this without adding a parameterless constructor to WithoutDefaultConstructor ? Here are the contents of MainWindow.xaml : <Window x:Class=

Using Visual Studio 2010 C++ with googlemock. I'm trying to use a mock I created and I'm getting the compiler error on the line: EmployeeFake employeeStub; The error is: 1>c:\someclasstests.cpp(22): error C2512: 'MyNamespace::EmployeeFake' : no appropriate default constructor available EmployeeFake: class EmployeeFake: public Employee{ public: MOCK_CONST_METHOD0(GetSalary, double()); } Employee: class Employee { public: Employee(PensionPlan *pensionPlan, const char * fullName); virtual ~Employee(void); virtual double GetSalary() const; } I gather that the problem is that the base class doesn't