Basically copying and pasting from Bjarne Stroustrup’s “The C++ Programming Language 4th Edition”: List initialization does not allow narrowing (§iso.8.5.4). That is: An integer cannot be converted to another integer that cannot hold its value. For example, char to int is allowed, but not int to char. A floating-point value cannot be converted to another … Read more
C++11 update to a very old question: Print variable type in C++. The accepted (and good) answer is to use typeid(a).name(), where a is a variable name. Now in C++11 we have decltype(x), which can turn an expression into a type. And decltype() comes with its own set of very interesting rules. For example decltype(a) … Read more
How is it a keyword and an instance of a type? This isn’t surprising. Both true and false are keywords and as literals they have a type ( bool ). nullptr is a pointer literal of type std::nullptr_t, and it’s a prvalue (you cannot take the address of it using &). 4.10 about pointer conversion … Read more
How to read: This article is rather long. If you want to know about both aggregates and PODs (Plain Old Data) take time and read it. If you are interested just in aggregates, read only the first part. If you are interested only in PODs then you must first read the definition, implications, and examples … Read more
I think it is too early to give a “best practices” answer for this as there hasn’t been enough time to use it in practice. If this was asked about throw specifiers right after they came out then the answers would be very different to now. Having to think about whether or not I need … Read more
The reason Herb said what he said is because of cases like this. Let’s say I have function A which calls function B, which calls function C. And A passes a string through B and into C. A does not know or care about C; all A knows about is B. That is, C is … Read more
Basic meaning and syntax Both keywords can be used in the declaration of objects as well as functions. The basic difference when applied to objects is this: const declares an object as constant. This implies a guarantee that once initialized, the value of that object won’t change, and the compiler can make use of this … Read more
1. “What is it?” While std::move() is technically a function – I would say it isn’t really a function. It’s sort of a converter between ways the compiler considers an expression’s value. 2. “What does it do?” The first thing to note is that std::move() doesn’t actually move anything. It changes an expression from being … Read more
It declares an rvalue reference (standards proposal doc). Here’s an introduction to rvalue references. Here’s a fantastic in-depth look at rvalue references by one of Microsoft’s standard library developers. CAUTION: the linked article on MSDN (“Rvalue References: C++0x Features in VC10, Part 2”) is a very clear introduction to Rvalue references, but makes statements about … Read more
In addition to what visitor said : The function void emplace_back(Type&& _Val) provided by MSCV10 is non conforming and redundant, because as you noted it is strictly equivalent to push_back(Type&& _Val). But the real C++0x form of emplace_back is really useful: void emplace_back(Args&&…); Instead of taking a value_type it takes a variadic list of arguments, … Read more