I tried the following code: int main() { int x {23.22}; } which includes an initialization that requires narrowing, but the code compiles fine without any error or warning. On the other hand, the following code gives error: int main() { int x[]{23.22}; } Have I found a bug or what? PS: I'm currently using GCC 4.5.0 ...
The following small example shows my problem: template<class T> struct X { static void xxx(T& x) { } static void xxx(T&& x) { } }; int main(int argc, char** argv) { int x = 9; X<int>::xxx(x); // OK. X<int&>::xxx(x); // ERROR! return 0; } Error message (GCC): error: ‘static void X::xxx(T&&) [with T = int&]’...
Hello everyone :) I'm still working on a good solution to my One-Of-A-Type Container Problem -- and upon reflection I think it would be nice to be able to just use something like a std::map<std::type_info, boost::any>. Unfortunately, std::type_info does not define an operator<, and I think it'd be unreasonable for it to define one. How...
In c++0x is there a way to template a lambda function? Or is it inherently too specific to be templated? I understand that I can define a classic templated class/functor instead but the question is more like : does the language allow templating lambda functions? ...
In perfect forwarding, std::forward is used to convert the named rvalue reference t1 and t2 to unnamed rvalue reference. What is the purpose of doing that? How would that effect the called function inner if we leave t1 & t2 as lvalue? template <typename T1, typename T2> void outer(T1&& t1, T2&& t2) { inner(std::forward<T1>(t1), std...
I have heard and read that C++0x allows an compiler to print "Hello" for the following snippet #include <iostream> int main() { while(1) ; std::cout << "Hello" << std::endl; } It apparently has something to do with threads and optimization capabilities. It looks to me that this can surprise many people though. Does someone...
Hi, I just discovered this old C++0x draft about modules in C++0x. The idea was to get out of the current .h/.cpp system by writing only .cpp files which would then generate module files during compilation, which would then in turn be used by the other .cpp files. This looks like a really great feature. But my question is: why did the...
In C++03, an expression is either an rvalue or an lvalue. In C++0x, an expression can be an: rvalue lvalue xvalue glvalue prvalue Two categories have become five categories. What are these new categories of expressions? How do these new categories relate to the existing rvalue and lvalue categories? Are the rvalue and lvalu...
Hi! I want to ask, does C++0x going to provide delegate ? If no, tell me what is the best way (most efficient) to use delegation in C++ ? Boost.Signals ? FastDelegate ? Or something other? ...
Hi, I have some original code that manages exception safety like this: void foo() { HDC hdc = //get an HDC HBITMAP hbitmap = //get an HBITMAP HGDIOBJ hbitmapOld = SelectObject(hdc, hbitmap); try { //do something that may throw an exception } catch (...) { SelectObject(hdc, hbitmapOld); thro...
I was just wondering if there was anything in the C++0x std lib already available to count the number of parameters in a parameter pack? I'd like to get rid of the field_count in the code below. I know I can build my own counter, but it just seems like this would be an obvious thing to include in the C++0x std lib, and I wanted to be s...
This question also applies to boost::function and std::tr1::function. std::function is not equality comparable: #include <functional> void foo() { } int main() { std::function<void()> f(foo), g(foo); bool are_equal(f == g); // Error: f and g are not equality comparable } The operator== and operator!= overloads are declared ...
Hi all, I have seen a lot of links introduced the variadic templates. But I have never seen one compilable example that demonstrates this approach? Could someone provides me some links in which such compilable examples can be found? regards Sami ...
Entity has a member var of type std::array. Student inherits from Entity, and will need to initialize the std::array member var it inherited. Below is the code I'm using to do this, but it involves casting a brace-enclosed list to std::array. I'm not sure this is the correct or optimal way to do this. Using a brace-enclosed or double...
Hi, One of my class' member method take as an argument of enumeration type: it produces different side effects for different enum. I was wondering whether it's possible to use template as a lookup table, two possible solutions came up to my mind, but none of them seems to work: //// 1 //// class A { public: enum AEnum : uint...
Why does this fail to compile? (g++-4.5) template < typename U > static void h () { } int main () { auto p = &h<int>; // error: p has incomplete type } EDIT: Here is a work-around: template < typename U > static void h () { } int main () { typedef decltype (&h<int>) D; D p = &h<int>; // works } ...
is there gonna be a new version for c++ and when? ...
How can be realized the auto keyword functionality without using c++0x standard? for(std::deque<std::pair<int, int> >::iterator it = points.begin(); it != points.end(); ++it) { ... } Maybe such class: class AUTO { public: template <typename T1> AUTO(T1); template <typename T2> operator T2(); }; With such usage: ...
The command g++ -o myprogram myprogram.c -std=c++0x works well on ubuntu but when I try the same with centos it throws me an error cc1plus: error: unrecognized command line option "-std=c++0x". Even google doesn't give the answer. Have anybody experienced it before? Does anybody know the solution? ...
Hi all, I am a little confused about how can I read each argument from the tuple by using variadic templates. Consider this function: template<class...A> int func(A...args){ int size = sizeof...(A); .... } I call it from the main file like: func(1,10,100,1000); Now, I don't know how I have to extend the body of func to be able to...