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.NET Forum / .NET Framework / CLR / May 2006Unmaged Code
Hello All I need to sak one question related to the CLR and Managed And Unmanage Code I read in the MSDN that ..... The code which is targetting CLR is managed code. The code which is not targetting CLR is unmanaged code Unmanged Code Means which directly interact with OS functionalty. If this concept is correct then i need to verify with the reason that , the statement "usage of Pointer in application mean that this code is unmanaged code" is true or false What?? with regards tarun sinha False. You have to use an unsafe context to use pointers in managed code, but that doesn't make it unmanaged. > Hello All > [quoted text clipped - 14 lines] > with regards > tarun sinha I didn't understand the word unsafe context .... can ou Please explain me abit Example: byte[] twoBytes; byte byteOne, byteTwo; twoBytes = new byte[] { 1, 2 }; unsafe { byte* ptr = &(asdf[0]); byteOne = *ptr; ptr++; byteTwo = *ptr; } > I didn't understand the word unsafe context .... can ou Please explain > me abit Thanks for repling me so soon ... if we using the pointer .that mean .we are dealing with unmange Code Can you suggest me manged Code using Pointer . Is it Possible ??? "I mean I want to Know existance of pointer in code make it unmanaged " Is this statement is true or false and why Please tell me the reason??? Thank You With regards tarun sinha > Thanks for repling me so soon ... > > if we using the pointer .that mean .we are dealing with unmange Code No. > Can you suggest me manged Code using Pointer . Is it Possible ??? Look at the code in my previous post. > "I mean I want to Know existance of pointer in code make it unmanaged " > Is this statement is true or false I already answered this in my first reply. > and why Please tell me the reason??? As for the reason: Why in the world would it make it unmanaged? It's obvious that you don't know the difference between managed and unmanaged code. Google some and read up on the basic principles of managed code. > Thanks for repling me so soon ... > > if we using the pointer .that mean .we are dealing with unmange Code > Can you suggest me manged Code using Pointer . Is it Possible ??? There are two things that can be managed/unmanaged: data and code. Managed code means, the compiler produces il instructions instead of raw machine code. When the program runs, the clr will compile the il to machine code as needed. Managed data means, you let the clr handle memory allocations and deallocations. The clr will sometimes move your data behind the scenes, so you generally can't trust pointers. The C# and VB.NET compilers always produce managed code that ususally works with managed data. However C# allows limited use of unmanaged data. With C++, you can produce managed code that works with a mix of managed and unmanaged data. Or you can produce unmanaged code that works with unmanaged data. Unmanaged code should not access managed data, except through COM interop or similar techniques. Hope this clears things up a bit. If not, just stay with the managed stuff and forget about pointers. ON you explain me but still i am in confusion of unmanged code and data. In a previous post you mention the statement "The clr will sometimes move your data behind the scenes" Please explain Further the above statement. One More thing sir, can you Please define unmanaged code and data in the similar way as you define manged code and data. Thank You With regards Tarun Sinha > you explain me but still i am in confusion of unmanged code and data. > In a previous post you mention the statement "The clr will sometimes > move your data behind the scenes" > Please explain Further the above statement. It's called compacting garbage collection. At unpredictable times, the clr will pause the execution of managed code and defragment memory by moving managed objects. Generally, you don't need to care about this unless you use pointers with managed objects. If you really need pointers into managed objects, you need to pin the objects. But don't unless you really have to. > One More thing sir, can you Please define unmanaged code > and data in the similar way as you define manged code and > data. "Unmanaged" simply means, it's not controlled or defined by the clr. A discussion of unmanaged code and data is really outside the scope of this newsgroup. The "usual" (unmanaged code) is produced by a compiler and it is immediatelly available to the CPU for running. This means that a program in unmanaged code is essentially a group of CPU instructions. Managed code is a "intermediate" state of code where you need an additional layer (virtual machine) in order to translate managed code to pure CPU instructions (that the CPU can understand). Garbage collection is not something particular to managed code. Managed code has to do with the need of an intermediate layer in order to execute it. This "intermediate layer" usually provides additional services like memory reclaiming mechanism, just in time compilers etc etc Pointer can be used in both managed/unmanaged code. The only difference is that the CLR (the .NET virtual machine) forces you to do this in an unsafe context. By saying unsafe that means that the pointer can show anywhere you like (and potentialy do something wrong). There is the IntPtr class in .net where you can use pointers outside of an unsafe context although in a limited fashion. Best regards, Tasos
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