using-directives

问题 Sorry for this silly question, but is there any way to restrict using directives to the current file so that they don't propagate to the files that #include this file? 回答1: Perhaps wrapping the code to be included inside its own namespace could achieve the behavior you want, since name spaces have scope affect. // FILENAME is the file to be included namespace FILENAME_NS { using namespace std; namespace INNER_NS { [wrapped code] } } using namespace FILENAME_NS::INNER_NS; and in some other

问题 When I use ReSharper to add a using directive (using Alt+Enter) it removes "unnecessary" parts of the namespace. I prefer using the full namespace which is also the behavior of Visual Studio. Example: namespace MyCompany.MyTool.Data { // This is what ReSharper gives me: using Core; // This is what I want: using MyCompany.MyTool.Core; // ... } Which setting do I have to change in ReSharper 4.5 so it uses the full namespace? 回答1: I don't have ReSharper 4.5 installed at the moment, but in 5.0

问题 There are convincing arguments against using namespace std , so why was it introduced into the language at all? Doesn't using namespace defeat the purpose of namespaces? Why would I ever want to write using namespace ? Is there any problem I am not aware of that is solved elegantly by using namespace , maybe in the lines of the using std::swap idiom or something like that? 回答1: For one thing, this is the way to use operator overloads in a namespace (e.g using namespace std::rel_ops; or using

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: What are the differences between typedef and using in C++11? The following code compiles and runs. My question is what is the difference between the "typedef" and "using" method for renaming the template specialization? template<typename T> struct myTempl{ T val; }; int main (int, char const *[]) { using templ_i = myTempl<int>; templ_i i; i.val=4; typedef myTempl<float> templ_f; templ_f f; f.val=5.3; return 0; }

问题 We are new to angularjs v4. We have a requirement of drilldown charts in google charts. We are using ng2-google-charts directives. We are able to find the select event and updated the data. but chart is not reloading. Could any one please help on this. view: index.html <pre> <br/> <google-chart #drillchart [data]='pieChartData' type="BarChart" (chartSelect)='select($event)'> </google-chart> </pre> Component.ts: pieChartData = { chartType: 'BarChart', dataTable: [ ['Country', 'Poulation'], [

问题 Sometimes I find code like the following (actually some class-wizards create such code): // C.h namespace NS { class C { void f(); }; } and in the implementation file: // C.cpp #include "C.h" using namespace NS; void C::f() { //... } All the compilers I tried accept that kind of code (gcc, clang, msvc, compileonline.com). What makes me feel uncomfortable is the using namespace NS; . From my point of view C::f() lives in the global namespace in an environment that has unqualified access to

问题 In VB.Net you can do something like the following without any issues... just ignore the fact that this is a pretty useless class :-) Imports System Public Class Class1 Public Shared Function ArrayToList(ByVal _array() As String) As Collections.Generic.List(Of String) Return New Collections.Generic.List(Of String)(_array) End Function End Class However if you do the same thing in C#... using System; public class Class1 { public static Collections.Generic.List ArrayToList(string[] _array) {

问题 I have got 5 C# files that have 20 using directives in common. I want to get rid of this code duplication, especially because these 20 using directives belong logically together. In C or C++ I would have created an extra header file containing these 20 include files. This extra header file acts as a layer then to include the 20 other files in one go. Unfortunately I don't know how to do this in C#. Any suggestions? 回答1: You can't do this in C# since C# does not have a preprocessor, and the C#

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Why is 'using namespace std;' considered a bad practice in C++? The other day when I asked a question someone replied saying if someone asks a question, show them the right way to do it instead of using namespace std; which I thought was a bit weird, as using namespace std; is way easier, But I guess I'm failing right now as I am a 'beginner' coder and you guys know better. So I guess my question is: Why std::

问题 This question may be a duplicate, but I can't find a good answer. Short and simple, what requires me to declare using namespace std; in C++ programs? 回答1: Since the C++ standard has been accepted, practically all of the standard library is inside the std namespace. So if you don't want to qualify all standard library calls with std:: , you need to add the using directive. However, using namespace std; is considered a bad practice because you are practically importing the whole standard