vs2010 C++示例中'^'是什么意思？

2013-04-23 06:58:34 267 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

Windows下VS2010编译PCRE Windows下VS2010编译PCRE 前言：下载PCRE源代码对源代码进行一些处理创建VS2010工程编译PCRE C语言使用PCRE的小例子快捷键加粗 Ctrl + B 斜体 Ctrl + I 引用 Ctrl + Q 插入链接 Ctrl + L 插入代码 Ctrl + K 插入图片 Ctrl + G 提升标题 Ctrl + H 有序列表阅读详情

vs2010C++示例中有问题不懂：
String^ str = " A String!";'^'这个符号是何用意呢，请赐教

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解决Visual C++2008安装失败，error 1935 重装系统后Visual C++没了，其他都能装上但VC2008会报这个error 1935。鉴于我把网上所有的解决方法排了一遍错，我也不知道是哪一步起效，所以就都放上来了。特别注意：报error 1935的错误原因可能不尽相同，比如我的报错开头为An error occurred，结尾为HRESULT：0x80070005。80070005 拒绝访问通常是权限问题，安装Visual C++无法写入文件夹或注册表（直接跳转第7步）阅读详情

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ForestDB 2013-04-24

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顶LS，C++/CLI。

赵4老师 2013-04-24

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查MSDN是Windows程序员必须掌握的技能之一。 ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/dv_vclang/html/70c411e6-be57-4468-a944-6ea7be89f392.htm Visual C++ Language Reference ^ (Handle to Object on Managed Heap) Example See Also Send Feedback Declares a handle to an object on the managed heap. Remarks A handle to an object on the managed heap points to the "whole" object, and not to a member of the object. See gcnew for information on how to create an object on the managed heap. In Visual C++ 2002 and Visual C++ 2003, __gc * was used to declare an object on the managed heap. The ^ replaces __gc * in the new syntax. The common language runtime maintains a separate heap on which it implements a precise, asynchronous, compacting garbage collection scheme. To work correctly, it must track all storage locations that can point into this heap at runtime. ^ provides a handle through which the garbage collector can track a reference to an object on the managed heap, thereby being able to update it whenever that object is moved. Because native C++ pointers (*) and references (&) cannot be tracked precisely, a handle-to object declarator is used. Member selection through a handle (^) uses the pointer-to-member operator (->). For more information, see How to: Declare Handles in Native Types. Example This sample shows how to create an instance of reference type on the managed heap. This sample also shows that you can initialize one handle with another, resulting in two references to same object on managed, garbage-collected heap. Notice that assigning nullptr to one handle does not mark the object for garbage collection. Copy Code // mcppv2_handle.cpp // compile with: /clr ref class MyClass { public: MyClass() : i(){} int i; void Test() { i++; System::Console::WriteLine(i); } }; int main() { MyClass ^ p_MyClass = gcnew MyClass; p_MyClass->Test(); MyClass ^ p_MyClass2; p_MyClass2 = p_MyClass; p_MyClass = nullptr; p_MyClass2->Test(); } Copy Code 1 2 The following sample shows how to declare a handle to an object on the managed heap, where the type of object is a boxed value type. The sample also shows how to get the value type from the boxed object. Copy Code // mcppv2_handle_2.cpp // compile with: /clr using namespace System; void Test(Object^ o) { Int32^ i = dynamic_cast<Int32^>(o); if(i) Console::WriteLine(i); else Console::WriteLine("Not a boxed int"); } int main() { String^ str = "test"; Test(str); int n = 100; Test(n); } Copy Code Not a boxed int 100 This sample shows that the common C++ idiom of using a void* pointer to point to an arbitrary object is replaced by Object^, which can hold a handle to any reference class. It also shows that all types, such as arrays and delegates, can be converted to an object handle. Copy Code // mcppv2_handle_3.cpp // compile with: /clr using namespace System; using namespace System::Collections; public delegate void MyDel(); ref class MyClass { public: void Test() {} }; void Test(Object ^ x) { Console::WriteLine("Type is {0}", x->GetType()); } int main() { // handle to Object can hold any ref type Object ^ h_MyClass = gcnew MyClass; ArrayList ^ arr = gcnew ArrayList(); arr->Add(gcnew MyClass); h_MyClass = dynamic_cast<MyClass ^>(arr[0]); Test(arr); Int32 ^ bi = 1; Test(bi); MyClass ^ h_MyClass2 = gcnew MyClass; MyDel^ DelInst = gcnew MyDel(h_MyClass2, &MyClass::Test); Test(DelInst); } Copy Code Type is System.Collections.ArrayList Type is System.Int32 Type is MyDel This sample shows that a handle can be dereferenced and that a member can be accessed via a dereferenced handle. Copy Code // mcppv2_handle_4.cpp // compile with: /clr using namespace System; value struct DataCollection { private: int Size; array<String^>^ x; public: DataCollection(int i) : Size(i) { x = gcnew array<String^>(Size); for (int i = 0 ; i < Size ; i++) x[i] = i.ToString(); } void f(int Item) { if (Item >= Size) { System::Console::WriteLine("Cannot access array element {0}, size is {1}", Item, Size); return; } else System::Console::WriteLine("Array value: {0}", x[Item]); } }; void f(DataCollection y, int Item) { y.f(Item); } int main() { DataCollection ^ a = gcnew DataCollection(10); f(*a, 7); // dereference a handle, return handle's object (*a).f(11); // access member via dereferenced handle } Copy Code Array value: 7 Cannot access array element 11, size is 10 This sample shows that a native reference (&) can’t bind to an int member of a managed type, .as the int may be stored in the garbage collected heap, and native references don’t track object movement in the managed heap. The fix is to use a local variable, or to change & to %, making it a tracking reference. Copy Code // mcppv2_handle_5.cpp // compile with: /clr ref struct A { void Test(unsigned int &){} void Test2(unsigned int %){} unsigned int i; }; int main() { A a; a.i = 9; a.Test(a.i); // C2664 a.Test2(a.i); // OK unsigned int j = 0; a.Test(j); // OK } Requirements Compiler option: /clr See Also Concepts Language Features for Targeting the CLR Send feedback on this topic to Microsoft.

Athenacle_ 2013-04-23

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clr 托管对象

vs2010 C++示例中'^'是什么意思？

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