}inti;voidfun(){ }usingA::fun;//此时使用了using declaration ,但是如果在名字空间A中,有多个重载的函数fun,此using declaration就把所有的fun都引入到了这个作用域中intmain(){ A::i=100;//访问A名字空间A中的i::i=1999;//访问全局名字空间中的i//fun();此时会出现冲突,无法分辨fun是A中的还是全局...
If a using-declaration or using-directive is used within a block, the names are applicable to just that block (it follows normal block scoping rules). This is a good thing, as it reduces the chances for naming collisions to occur to just within that block. If a using-declaration or usin...
using std::cout (using declaration) using namespace std (using directive) /clr The following sample shows how to allow names in a .NET Framework SDK base class library namespace to be used without the namespace-name as an explicit qualifier. 复制 // using_directive.cpp // compile wit...
:swap technique when I first read this, because I knew you weren't just asking about the [dis-]advantages of certain scoping practices, but it sounded like you were looking for an end-result that used a 'using directive' and not a 'using declaration'. Ah well, glad you remembered it!
See using Directive for more information. Example A using declaration can be used in a class definition. 复制 // using_declaration1.cpp #include <stdio.h> class B { public: void f(char) { printf_s("In B::f()\n"); } void g(char) { printf_s("In B::g()\n"); } }; ...
Why not produce a warning for this, so that you can remove the useless directive from your program?Suppose we make an unused using into a warnings. Suppose you do have “warnings are errors” turned on. And suppose you create a new console project in Visual Studio. We generate you th...
CGAL_CFG_NO_WARNING_CPP_DIRECTIVE_BUG - Failed Performing Test CGAL_CFG_NUMERIC_LIMITS_BUG - Success Performing Test CGAL_CFG_OUTOFLINE_MEMBER_DEFINITION_BUG - Success Performing Test CGAL_CFG_TEMPLATE_IN_DEFAULT_PARAMETER_BUG - Success Performing Test CGAL_CFG_TYPENAME_BEFORE_DEFAULT_ARGUMENT_BUG...
Error_96_The type or namespace name 'Button' could not be found (are you missing a using directive or an assembly reference?)_ Error: An object reference is required for the non-static field, method, or property ERROR: Anonymously Hosted DynamicMethods Assembly ERROR: Unable to cast object ...
You may not use ausing-directiveto make all names from a namespace available. // Forbidden -- This pollutes the namespace. using namespace foo; You may use ausing-declarationanywhere in a.ccfile, and in functions, methods or classes in.hfiles. ...
The OPTION EXPLICIT directive forces explicit declaration of all variables in the file. Setting UniqueFiles to "ON" ensures that destination files are unique. "ON" is the default value, because using the same file name twice usually means that the same file was accidentally included twice, which...