How to copy/convert System::Object^(unsigned char) to local variable - Managed C++/CLI Discussion Boards

Re: Questions about string manipulation [modified]

TabascoSauce21-Apr-09 15:59

TabascoSauce

21-Apr-09 15:59

Thanks N a v a n e e t h!

**Edit

Ok, I got it now! Thanks very much!

modified on Tuesday, April 21, 2009 10:06 PM

Executing Code on App Exit

turkmeistr120-Apr-09 9:16

turkmeistr1

20-Apr-09 9:16

I have a project that I'm working on that generates batch files when a button is clicked. I added a close button that then cleans the subdirectory the batch files are generated in. The only problem I'm experiencing now is that when the user closes the application using the builtin x button in the upper right hand corner, it doesn't execute the code since it calls it's own destructor. Is there any way to have that close feature also clean the subdirectory by removing all the *.bat files?

Re: Executing Code on App Exit

Luc Pattyn20-Apr-09 9:22

Luc Pattyn

20-Apr-09 9:22

Hi,

you might put your exit code in the mainform's FormClosed event handler.

Smile | :)

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Re: Executing Code on App Exit

turkmeistr120-Apr-09 9:32

turkmeistr1

20-Apr-09 9:32

I created this app using Visual C++, sorry to sound really stupid, but where exactly would I find that? I'm more of a console programmer but recently decided to try and tackle GUIs.

Re: Executing Code on App Exit

Luc Pattyn20-Apr-09 9:40

Luc Pattyn

20-Apr-09 9:40

You know how to add a Button.Click handler? or a TextBox.TextChanged handler?
It is exactly the same for Form.FormClosed: in Visual Designer select the Control, right click for Properties, use Lightning icon to switch to events, double-click the event you want, that adds and opens the handler's method.

Smile | :)

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Re: Executing Code on App Exit

turkmeistr120-Apr-09 10:01

turkmeistr1

20-Apr-09 10:01

Awesome! That was very helpful! Thank you so much!

Re: Executing Code on App Exit

Luc Pattyn20-Apr-09 10:03

Luc Pattyn

20-Apr-09 10:03

You're welcome.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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How to copy/convert System::Object^(unsigned char) to local variable

marcusab18-Apr-09 10:27

marcusab

18-Apr-09 10:27

I would like to copy the data content of pDataByte to QByte using Microsoft Visual C++ 2008 .NET

Debug Info

Name         Value           Type
pDataByte    {System.Array}  System::Object^
 [0x0]       0x41 ‘A’        unsigned char
 [0x1]       0x42 ‘B’        unsigned char
 [0x2]       0x43 ‘C’        unsigned char
 [0x3]       0x44 ‘D’        unsigned char

QByte        {Length=0x4}    unsigned char[]
 [0x0]       0x00 ‘’         unsigned char
 [0x1]       0x00 ‘’         unsigned char
 [0x2]       0x00 ‘’         unsigned char
 [0x3]       0x00 ‘’         unsigned char

I have tried several approaches, for example:

<br />
//Declare variables<br />
System::Object ^pDataByte;<br />
unsigned char QByte[4];<br />
<br />
//External DLL Function<br />
ReadOutput(pDataByte);<br />
<br />
//Current variable status see "Debug Info"<br />
<br />
//Copy values to local variable<br />
QByte[0] = (unsigned char)System::Convert::ToChar(pDataByte); <br />

Error Code (at runtime at line: QByte[0] = (unsigned char)System...)
An unhandled exception of type 'System.InvalidCastException' occurred in mscorlib.dll
Additional information: Unable to cast object of type 'System.Byte[]' to type 'System.IConvertible'.

Please help, I have tried very hard to get this to work, I am used to plane C++ (not .NET Framework) Sniff | :^)

Re: How to copy/convert System::Object^(unsigned char) to local variable

N a v a n e e t h18-Apr-09 16:42

N a v a n e e t h

18-Apr-09 16:42

What is the type of the content in pDataByte? Is that a byte array?

Navaneeth

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Re: How to copy/convert System::Object^(unsigned char) to local variable

marcusab18-Apr-09 23:30

marcusab

18-Apr-09 23:30

Yes, unsigned char (8-bit, byte) system array to be more specific, see "Debug Info".

Debug Info

Name         Value           Type
pDataByte    {System.Array}  System::Object^
 [0x0]       0x41 ‘A’        unsigned char
 [0x1]       0x42 ‘B’        unsigned char
 [0x2]       0x43 ‘C’        unsigned char
 [0x3]       0x44 ‘D’        unsigned char

QByte        {Length=0x4}    unsigned char[]
 [0x0]       0x00 ‘’         unsigned char
 [0x1]       0x00 ‘’         unsigned char
 [0x2]       0x00 ‘’         unsigned char
 [0x3]       0x00 ‘’         unsigned char

Re: How to copy/convert System::Object^(unsigned char) to local variable

N a v a n e e t h19-Apr-09 6:41

N a v a n e e t h

19-Apr-09 6:41

// Following line is wrong. pDataByte is an object with type as System.Array. 
// You can't cast it as unsigned char
QByte[0] = (unsigned char)System::Convert::ToChar(pDataByte);

First you need to get a unsigned char array from the object. Loop through each element and assign it to QByte. Sample code follows,

// Getting unsigned array from pDataByte
array<unsigned char>^ uChars = static_cast<array<unsigned char>^>(pDataByte);

// filling QByte
for(int i=0; i < uChars->Length; i++)
{
    QByte[i] = uChars[i];
}

Hope that helps Smile | :)

Navaneeth

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Re: How to copy/convert System::Object^(unsigned char) to local variable [modified]

marcusab19-Apr-09 11:04

marcusab

19-Apr-09 11:04

Thanks a lot, that´s not enough, thank you, thank you, thank you!

I used your solution together with the solution from Mark Salsbery

array<unsigned char>^ uChars = static_cast<array<unsigned char>^>(pDataByte);
System::Runtime::InteropServices::Marshal::Copy(uChars, 0, System::IntPtr(QByte), 4);

Thank you both extremely much

modified on Monday, April 20, 2009 5:44 AM

Re: How to copy/convert System::Object^(unsigned char) to local variable

N a v a n e e t h19-Apr-09 15:34

N a v a n e e t h

19-Apr-09 15:34

Happy to see it worked Smile | :)

Navaneeth

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Re: How to copy/convert System::Object^(unsigned char) to local variable

Luc Pattyn19-Apr-09 16:10

Luc Pattyn

19-Apr-09 16:10

Of course it worked, three people working as a team should be sufficient to move 4 bytes OMG | :OMG:

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Re: How to copy/convert System::Object^(unsigned char) to local variable

N a v a n e e t h19-Apr-09 17:02

N a v a n e e t h

19-Apr-09 17:02

Luc Pattyn wrote:
three people working as a team should be sufficient to move 4 bytes

Great! Worth for a new sig.

Smile | :)

Navaneeth

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Re: How to copy/convert System::Object^(unsigned char) to local variable

Mark Salsbery20-Apr-09 8:31

Mark Salsbery

20-Apr-09 8:31

Obviously, four people would have been the most efficient team size for this project - one person per byte Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: How to copy/convert System::Object^(unsigned char) to local variable

Luc Pattyn20-Apr-09 8:40

Luc Pattyn

20-Apr-09 8:40

If they all spend their time reading The Mythical Man-Month four people may not even be enough...

PS: have been reading some Joel-on-Software lately, so I couldn't join in, sorry.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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Re: How to copy/convert System::Object^(unsigned char) to local variable

Mark Salsbery19-Apr-09 6:40

Mark Salsbery

19-Apr-09 6:40

marcusab wrote:
I would like to copy the data content of pDataByte to QByte

Here's two ways:

array<Byte> ^pDataByte = gcnew array<Byte>(4);
pDataByte[0] = 0x41;
pDataByte[1] = 0x42;
pDataByte[2] = 0x43;
pDataByte[3] = 0x44;

unsigned char QByte[4];

// Use a pinning pointer
pin_ptr<Byte> p = &pDataByte[0];
memcpy(QByte, p, 4);

// Use Marsal.Copy()
Marshal::Copy(pDataByte, 0, IntPtr(QByte), 4);

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: How to copy/convert System::Object^(unsigned char) to local variable

marcusab19-Apr-09 10:55

marcusab

19-Apr-09 10:55

Thank you very very very much , you got me going in the right direction, see my answer to Navaneeth for more info.

Almost, pDataByte is a System::Object^ {System.Array}, not an array<unsigned char=""> {Length = 0x4} as with QByte. See debug info:

Name         Value           Type
pDataByte    {System.Array}  System::Object^
 [0x0]       0x41 ‘A’        unsigned char
 [0x1]       0x42 ‘B’        unsigned char
 [0x2]       0x43 ‘C’        unsigned char
 [0x3]       0x44 ‘D’        unsigned char
QByte        {Length=0x4}    unsigned char[]
 [0x0]       0x00 ‘’         unsigned char
 [0x1]       0x00 ‘’         unsigned char
 [0x2]       0x00 ‘’         unsigned char
 [0x3]       0x00 ‘’         unsigned char

So I get compilation error:

<br />
error C2665: 'System::Runtime::InteropServices::Marshal::Copy' : none of the 16 overloads could convert all the argument types<br />

Re: How to copy/convert System::Object^(unsigned char) to local variable

Mark Salsbery19-Apr-09 11:12

Mark Salsbery

19-Apr-09 11:12

marcusab wrote:
pDataByte is a System::Object^ {System.Array}, not an array

An array IS a System.Array, but I missed your declaration - sorry about that!

You need the cast Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: How to copy/convert System::Object^(unsigned char) to local variable

marcusab19-Apr-09 11:32

marcusab

19-Apr-09 11:32

By the way, how do I create the variable pDataByte (now I recevie it from an external DLL).

I would like to do someting like this:

System::Object ^pDataByte = gcnew System::Object(System::Array<<System::Byte>>(4));

To get this:

Name         Value           Type
pDataByte    {System.Array}  System::Object^
 [0x0]       0x00 ‘’         unsigned char
 [0x1]       0x00 ‘’         unsigned char
 [0x2]       0x00 '’         unsigned char
 [0x3]       0x00 ‘’         unsigned char

Re: How to copy/convert System::Object^(unsigned char) to local variable

marcusab19-Apr-09 11:44

marcusab

19-Apr-09 11:44

Never mind ... D'Oh! | :doh:

System::Object ^pDataByte = gcnew array<System::Byte>(4);

Again, thank you very much Smile | :)

Re: How to copy/convert System::Object^(unsigned char) to local variable

Mark Salsbery19-Apr-09 11:44

Mark Salsbery

19-Apr-09 11:44

Why not use the strong type instead of a System::Object^ ?

array<Byte> ^pDataByte = gcnew array<Byte>(4);

If you must use System::Object^...

System::Object ^pDataByte = gcnew array<Byte>(4);

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: How to copy/convert System::Object^(unsigned char) to local variable

marcusab19-Apr-09 11:57

marcusab

19-Apr-09 11:57

Thanks again, you are the man Smile | :)

DialogBox in C++/CLI

J_E_D_I9-Apr-09 11:29

J_E_D_I

9-Apr-09 11:29

Hi, I can't find any decent example on how to create a DialogBox using C++/CLI and on how to deal with the different responses triggered by the diffent buttons being pressed.

I've created graphically the DialogBox (form2) which has 2 buttons "A" and "B" but I can't understand how I can pass different values to the main form (form1) when each button is selected. Is it possible to do it without creating a new class. How?

Any example code would be highly appreciated.

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