I know the title sounds familiar as there are many similar questions, but I’m asking for a different aspect of the problem (I know the difference between having things on the stack and putting them on the heap). In Java I can always return references to “local” objects public Thing calculateThing() { Thing thing = … Read more
Something I have found myself doing often lately is declaring typedefs relevant to a particular class inside that class, i.e. class Lorem { typedef boost::shared_ptr<Lorem> ptr; typedef std::vector<Lorem::ptr> vector; // // … // }; These types are then used elsewhere in the code: Lorem::vector lorems; Lorem::ptr lorem( new Lorem() ); lorems.push_back( lorem ); Reasons I … Read more
In his book The C++ Standard Library (Second Edition) Nicolai Josuttis states that lambdas can be better optimized by the compiler than plain functions. In addition, C++ compilers optimize lambdas better than they do ordinary functions. (Page 213) Why is that? I thought when it comes to inlining there shouldn’t be any difference any more. … Read more
In c++14 the decltype(auto) idiom is introduced. Typically its use is to allow auto declarations to use the decltype rules on the given expression. Searching for examples of “good” usage of the idiom I can only think of things like the following (by Scott Meyers), namely for a function’s return type deduction: template<typename ContainerType, typename … Read more
Suppose I have a class with private memebers ptr, name, pname, rname, crname and age. What happens if I don’t initialize them myself? Here is an example: class Example { private: int *ptr; string name; string *pname; string &rname; const string &crname; int age; public: Example() {} }; And then I do: int main() { … Read more
I got this question when I received a code review comment saying virtual functions need not be inline. I thought inline virtual functions could come in handy in scenarios where functions are called on objects directly. But the counter-argument came to my mind is — why would one want to define virtual and then use … Read more
How do I capture by move (also known as rvalue reference) in a C++11 lambda? I am trying to write something like this: std::unique_ptr<int> myPointer(new int); std::function<void(void)> example = [std::move(myPointer)]{ *myPointer = 4; }; 6 Answers 6
I am wondering what the difference is between typeid and typeof in C++. Here’s what I know: typeid is mentioned in the documentation for type_info which is defined in the C++ header file typeinfo. typeof is defined in the GCC extension for C and in the C++ Boost library. Also, here is test code test … Read more
In C++, Why is a boolean 1 byte and not 1 bit of size? Why aren’t there types like a 4-bit or 2-bit integers? I’m missing out the above things when writing an emulator for a CPU 13 Answers 13
So I’ve been getting some mysterious uninitialized values message from valgrind and it’s been quite the mystery as of where the bad value originated from. Seems that valgrind shows the place where the unitialised value ends up being used, but not the origin of the uninitialised value. ==11366== Conditional jump or move depends on uninitialised … Read more