BioRadio程序涉及到的知识点

1.关于GCroots和gcnew.

    常说的GC(Garbage Collector) roots，特指的是垃圾收集器（Garbage Collector）的对象，GC会收集那些不是GC roots且没有被GC roots引用的对象。C /CLI中使用gcnew关键字表示在托管堆上分配内存，并且为了和以前的指针区分，用^来替换* ，就语义上来说他们的区别大致如下:

　　1. gcnew返回的是个句柄(Handle)，而new返回的是实际的内存地址. 

　　2. gcnew创建的对象由虚拟机托管，而new创建的对象必须自己来管理和释放.

几个代码实例：

using namespace System;
ref class Foo
{
public:
Foo()
{
System::Console::WriteLine("Foo::Foo");
}
~Foo()
{
System::Console::WriteLine("Foo::~Foo");
}
public:
int m_iValue;
};
int _tmain()
{
int* pInt = new int;
int^ rInt = gcnew int;
Foo^ rFoo = gcnew Foo;
delete rFoo;
delete rInt;
delete pInt;
}

// mcpp_gcroot.cpp
// compile with: /clr
#include <vcclr.h>
using namespace System;

class CppClass {
public:
   gcroot<String^> str;   // can use str as if it were String^
   CppClass() {}
};

int main() {
   CppClass c;
   c.str = gcnew String("hello");
   Console::WriteLine( c.str );   // no cast required
}

// mcpp_gcroot_2.cpp
// compile with: /clr
// compile with: /clr
#include <vcclr.h>
using namespace System;

struct CppClass {
   gcroot<String ^> * str;
   CppClass() : str(new gcroot<String ^>) {}

   ~CppClass() { delete str; }

};

int main() {
   CppClass c;
   *c.str = gcnew String("hello");
   Console::WriteLine( *c.str );
}

// mcpp_gcroot_3.cpp
// compile with: /clr
#include < vcclr.h >
using namespace System;

public value struct V {
   String^ str;
};

class Native {
public:
   gcroot< V^ > v_handle;
};

int main() {
   Native native;
   V v;
   native.v_handle = v;
   native.v_handle->str = "Hello";
   Console::WriteLine("String in V: {0}", native.v_handle->str);
}