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Hi friends,

Can somebody tell me that how to sent date-time from C++ side to C# side. On C# side I used date-time as follows:
void WriteTextAppLog(DateTime dt, LogLevel level, string msgHeader, string msgDetails);
Now I want to sent date-time from C++ side to C# side in the form of above format.

I am using vc++ 2005.

Please help me to resolve this.

Posted 1-May-13 7:10am
Unmanaged C++ or C++/CLI (but, in second case, it should not be a problem to ask about)?

1 solution

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Solution 2

As the problem is trivial for C# vs C++/CLI, I can assume that you are talking about native (unmanaged) C++ project.

As System.DataTime is a CLI structure, you cannot use its reference in unmanaged code. You have to use Windows date-time structure, pass it to managed code, and convert it to System.DataTime on the CLI side (in C#).

In particular, you can use Windows FILETIME:[^].

As you can see, this is a 64-bit integer value composed as a record of two 32-bit values. You can pass it to C#, and convert to one 64-bit value (do you know how?). It will give you the time in 100-ns intervals. Use this value to initialize DataTime value using one of these constructors:[^],[^].

A more advanced way would be using customizing parameter marshalling, which is still done on the CLI side (C#) and would essentially do the same. To get an idea, please see:[^].

I hope you know that you can import native C++ function using P/Invoke and know how. If not, please refer to:[^],[^].

This CodeProject article can also be useful: Essential P/Invoke[^].

Mike Meinz 1-May-13 13:29pm
I deleted my answer and rated yours 5.
I appreciate your understanding of this matter.
Thank you, Mike.
Philippe Mori 2-May-13 0:33am
There is also a possibility to convert from/to OLE automotion time.
I don't see the difference... perhaps I don't understand what's "OLE automation time". Isn't it the same, by value?
Philippe Mori 2-May-13 8:45am
It is the time in a double as it was used in COM interfaces. Although I think that mapping would works automatically when importing a COM type library, I don't see any information for using it through P/Invoke thus it might not be supported in that case.

It seems that OLE automotion date would be the same value as the one in Excel when a date is displayed as a floating point number.
Thank you, Philippe. It would be easy to check up...
Vaibhav_J_Jaiswal 2-May-13 6:27am
I have a structure 'SYSTEMTIME systemTime' which stores all details of date-time. Can I send this structure to C# side. If yes then how?
By value: SomeMethod(SYSTEMTIME time), on both sides. Are you familiar with PInvoke?

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