ptr::operator!
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Operator to determine if the owned COM object is invalid.
Syntax
bool operator!();
Return Value
true if the owned COM object is invalid; false otherwise.
Remarks
The owned COM object is valid if it is not nullptr.
Example
This example implements a CLR class that uses a com::ptr to wrap its private member IXMLDOMDocument object. The CreateInstance member function uses operator! to determine if a document object is already owned, and only creates a new instance if the object is invalid.
// comptr_op_not.cpp
// compile with: /clr /link msxml2.lib
#include <msxml2.h>
#include <msclr\com\ptr.h>
#import <msxml3.dll> raw_interfaces_only
using namespace System;
using namespace System::Runtime::InteropServices;
using namespace msclr;
// a ref class that uses a com::ptr to contain an
// IXMLDOMDocument object
ref class XmlDocument {
public:
void CreateInstance(String^ progid) {
if (!m_ptrDoc) {
m_ptrDoc.CreateInstance(progid);
if (m_ptrDoc) {
Console::WriteLine("DOM Document created.");
}
}
}
// note that the destructor will call the com::ptr destructor
// and automatically release the reference to the COM object
private:
com::ptr<IXMLDOMDocument> m_ptrDoc;
};
// use the ref class to handle an XML DOM Document object
int main() {
try {
XmlDocument doc;
// create the instance from a progid string
doc.CreateInstance("Msxml2.DOMDocument.3.0");
}
catch (Exception^ e) {
Console::WriteLine(e);
}
}
DOM Document created.
Requirements
Header file <msclr\com\ptr.h>
Namespace msclr::com