I came across the following code: template <typename T, typename T1> auto compose(T a, T1 b) -> decltype(a + b) { return a+b; } There is one thing I cannot understand: Where could I find out what the arrow operator (->) means in the function heading? I guess purely logically, that the -> operator determines … 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
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
If I declare a base class (or interface class) and specify a default value for one or more of its parameters, do the derived classes have to specify the same defaults and if not, which defaults will manifest in the derived classes? Addendum: I’m also interested in how this may be handled across different compilers … Read more
I’ve read and heard that C++11 supports Unicode. A few questions on that: How well does the C++ standard library support Unicode? Does std::string do what it should? How do I use it? Where are potential problems? 5 Answers 5
I am new to C++11. I am writing the following recursive lambda function, but it doesn’t compile. sum.cpp #include <iostream> #include <functional> auto term = [](int a)->int { return a*a; }; auto next = [](int a)->int { return ++a; }; auto sum = [term,next,&sum](int a, int b)mutable ->int { if(a>b) return 0; else return term(a) … Read more
From all the material I used to learn C++, auto has always been a weird storage duration specifier that didn’t serve any purpose. But just recently, I encountered code that used it as a type name in and of itself. Out of curiosity I tried it, and it assumes the type of whatever I happen … Read more
Why does the reverse function for the std::list class in the C++ standard library have linear runtime? I would think that for doubly-linked lists the reverse function should have been O(1). Reversing a doubly-linked list should just involve switching the head and the tail pointers. 7 Answers 7
Just a small query regarding shared_ptr. Is it a good practice to use shared_ptr pointing to an array? For example, shared_ptr<int> sp(new int[10]); If not, then why not? One reason I am already aware of is one can not increment/decrement the shared_ptr. Hence it can not be used like a normal pointer to an array. … Read more
What is the logic behind the “using” keyword in C++? It is used in different situations and I am trying to find if all those have something in common and there is a reason why the “using” keyword is used as such. using namespace std; // to import namespace in the current namespace using T … Read more