They are equivalent, from the standard (emphasis mine) (7.1.3.2): A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword becomes a typedef-name and the optional attribute-specifier-seq following the identifier appertains to that typedef-name. It has the same semantics as if it were introduced by the typedef specifier. In particular, it … Read more
I guess this document might serve as a not so short introduction : n3055 The whole massacre began with the move semantics. Once we have expressions that can be moved and not copied, suddenly easy to grasp rules demanded distinction between expressions that can be moved, and in which direction. From what I guess based … Read more
The problem C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function. #include <algorithm> #include <vector> namespace { struct f { void operator()(int) { // do something … Read more
It’s very unfortunate that you see dynamic allocation so often. That just shows how many bad C++ programmers there are. In a sense, you have two questions bundled up into one. The first is when should we use dynamic allocation (using new)? The second is when should we use pointers? The important take-home message is … Read more
I find it easiest to understand move semantics with example code. Let’s start with a very simple string class which only holds a pointer to a heap-allocated block of memory: #include <cstring> #include <algorithm> class string { char* data; public: string(const char* p) { size_t size = std::strlen(p) + 1; data = new char[size]; std::memcpy(data, … Read more
UPDATE This answer is rather old, and so describes what was ‘good’ at the time, which was smart pointers provided by the Boost library. Since C++11, the standard library has provided sufficient smart pointers types, and so you should favour the use of std::unique_ptr, std::shared_ptr and std::weak_ptr. There was also std::auto_ptr. It was very much … Read more
First, you have to learn to think like a Language Lawyer. The C++ specification does not make reference to any particular compiler, operating system, or CPU. It makes reference to an abstract machine that is a generalization of actual systems. In the Language Lawyer world, the job of the programmer is to write code for … Read more