Re: Workaround global variables? - C# Discussion Boards

Re: can u help me with a if question?

7-Sep-07 3:12

Sorry, I don't understand what you are trying to accomplish.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

andredani7-Sep-07 5:13

andredani

7-Sep-07 5:13

when i press a button on a selected listview.item its gonna copy that item and pass it to the same listview but it gonna controle subitem[4] in a .txt file that there are no one else with that name. If there is then add +1....

Know it´s hard, even to excplain!! Big Grin | :-D

Gonna work the hole friday night, with this OMG | :OMG:

Re: can u help me with a if question?

Luc Pattyn5-Sep-07 9:59

Luc Pattyn

5-Sep-07 9:59

lines[0] is the first line

lines[0][0] is the first char of the first line (but could throw an exception if
lines[0] is null or an empty string.

when checking for a single char, use '#' instead of "#"

string.StartsWith("#") seems appropriate here.
maybe you want to trim the line (with string.Trim()) before checking for #

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google

Re: can u help me with a if question? [modified]

andredani5-Sep-07 11:31

andredani

5-Sep-07 11:31

What i´m trying to do is i have whrote a code and the user adds a path to a .txt file. And the user can add more paths so i thougt that: if line[21] have text go on with this code...

Tnx mates!!

-- modified at 17:37 Wednesday 5th September, 2007

Workaround global variables?

MeLight5-Sep-07 8:36

MeLight

5-Sep-07 8:36

Hello,
I understand that there's no such thing in C# as global variables, but I still need them Unsure | :~

Any known workaround or something else I'm missing here? thanx

TJoe5-Sep-07 8:52

5-Sep-07 8:52

You can define static classes and static fields like so:

public class GlobalVars {
    public static Int32 MyInt = 0;
}

You can then access that field from anywhere like so:

GlobalVars.MyInt = 1;
// ...
Int32 i = GlobalVars.MyInt;

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Christian Graus5-Sep-07 8:53

Christian Graus

5-Sep-07 8:53

90% of the time, you don't need them at all. The other 10%, create a static class, and make the variables members of it.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Larantz5-Sep-07 8:53

Larantz

5-Sep-07 8:53

This question has been asked, reasked, answered and reanswered exponentially I think. Smile | :)

No there are no global variables in C#.
If you want the closest match to a global variabel, you create a public static class and expose a public member variable for use as a 'globalish' variabel. Remember that you don't have to instanciate the class to access the variabel. Just use the class name directly.
I.e:

public static GlobalishVariabelHolder
{
   private static int globalishIntegerVariabel = 0;
   public static int GlobalishIntegerVariabel
   {
      get { return globalishIntegerVariabel;}
      set { globalishIntegerVariabel = value;}
   }
}

//accessing the static variable from other classes is done by:
private void someMethod()
{
    int value = GlobalishVariabelHolder.GlobalishIntegerVariabel;
    //do something with the value.
}

-Larantz-

for those about to code, we salute you
http://www.tellus-software.com

Thanx

MeLight5-Sep-07 8:57

MeLight

5-Sep-07 8:57

Bah, I should have thought of it myself D'Oh! | :doh:

Thanx

Dave Kreskowiak5-Sep-07 9:08

Dave Kreskowiak

5-Sep-07 9:08

And in the world of OOP, if you're trying to use global variables extensively, this is usually a sign of a bad design.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

sizeof

dino20945-Sep-07 8:26

dino2094

5-Sep-07 8:26

Hi,

I'm trying to write a method that is passed an array and do some bit operations. I'm trying to figure out a way to determine the number of bits an element of the arrray. I could hardcode the value but I'd like the flexibility just changing the header and nothing else.

int count(Uint16[] data){

//Try to do something like
int bitsInCell = sizeof(data[0])*8;

//Instead of
int bitsInCell = 16;

}

I'm trying to do it the first way so if I want to sent Uint32, I don't have to search the code for 16 and switch them to 32.

Thanks for your comments.

TJoe5-Sep-07 8:50

5-Sep-07 8:50

You can use the Marshal class, which is defined in System.Runtime.InteropServices, like so:

int bitsInCell = Marshal.SizeOf(data[0]) * 8;

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Luc Pattyn5-Sep-07 10:02

Luc Pattyn

5-Sep-07 10:02

Warning: Marshal.Sizeof() and sizeof() do not always agree. Try bool !

Luc Pattyn [Forum Guidelines] [My Articles]

TJoe5-Sep-07 10:19

5-Sep-07 10:19

Good point. Technically, Boolean (bool) in C# maps to BOOL (int) in C++. Probably because bool is not used in the Win32 API.

Plus, I believe a C++ long in a 64-bit environment will be 64 bits, but the C# int (a.k.a. Int32) is 32-bits.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Problem passing data to an activeX

dino20945-Sep-07 11:54

dino2094

5-Sep-07 11:54

Thank you my good man!

Paolo Vernazza5-Sep-07 6:55

Paolo Vernazza

5-Sep-07 6:55

I'm using in a project an activeX component with these 3 methods:

<br />
public void PutData(ref int pData, int nBytes);<br />
public int GetDataSize();<br />
public void GetData(ref int pData);<br />

The same functions, in a c++ project are:

<br />
void PutData(long* pData, long nBytes);<br />
long GetDataSize();<br />
void GetData(long* pData);<br />

With the first function I pass a buffer to the component and the component copies it in its own buffer.
With the third function I pass a buffer to the component and the component copies in my buffer the data that it previously stored in its own buffer.

I can't get the component work properly, because it seems to copy only the first 4 bytes (= the first integer).

I tried the component in a c++ project and it works properly, so I think that the problem is in the way I'm passing the data to the activex.

I use the functions in this way:

<br />
int[] buffer = new int[10];<br />
int[] buffer_check = new int[10];<br />
<br />
for (int i=0; i<10; i++)<br />
    buffer[i] = i;<br />
<br />
ocx.PutData(ref buffer[0], 10*sizeof(int));<br />
<br />
//That's works OK<br />
System.Diagnostics.Debug.Assert(ocx.GetDataSize() == 10*sizeof(int));<br />
<br />
ocx.GetData(ref buffer_check[0], 10*sizeof(int)); <br />
<br />
//This fails for any i != 0<br />
for (i=0; i<10; i++)<br />
      System.Diagnostics.Debug.Assert(buffer_check[i] == buffer[i]);<br />

Someone has any idea about what I'm doing wrong?
Thanks!

Paolo

TJoe5-Sep-07 8:23

5-Sep-07 8:23

Hi Paolo,

The ActiveX is expecting a pointer to, presumably, an array of long values. But from C# you are only passing a single Int32. You need to use an IntPtr to pass the data back and forth, like so:

// Create buffer
Int32[] buffer = new Int32[10];
buffer[5] = 1;

// Allocate and copy to unmanaged memory
IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)) * 10);
Marshal.Copy(buffer, 0, ptr, 10);

// Change buffer, so we can see that the ptr has restores the
//   old value
buffer[5] = 2;

// Copy from unmanged memory back to array
Marshal.Copy(ptr, buffer, 0, 10);

// Free memory, or else we will leak it
Marshal.FreeHGlobal(ptr);

Note: The Marshal class is in the System.Runtime.InteropServices namespace.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Paolo Vernazza6-Sep-07 1:57

Paolo Vernazza

6-Sep-07 1:57

It doesn't work Frown | :(

Your code works, but it stops if I use different unmanaged memory areas when storing and when retrieving or if I change the data in the unmanaged memory.

For example, this code doesn't work:

<br />
// Create buffer<br />
Int32[] buffer = new Int32[10];<br />
buffer[5] = 1;<br />
<br />
// Allocate and copy to unmanaged memory<br />
IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)) * 10);<br />
Marshal.Copy(buffer, 0, ptr, 10);<br />
<br />
// **** Need to add this, otherwise c# complains about not being able to convert IntPtr to int<br />
int bptr = (int)ptr;<br />
ocx.PutData(ref bptr, Marshal.SizeOf(typeof(Int32)) * 10);<br />
<br />
// Change buffer, so we can see that the ptr has restored the<br />
//   old value<br />
buffer[5] = 2;<br />
<br />
// **** Allocate another are to retrieve data<br />
IntPtr ptr2 = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)) * 10);<br />
int bptr2 = (int)ptr2;<br />
<br />
ocx.GetData(ref bptr2);<br />
// **** Here there is the problem: when GetData() returns, <br />
// the bptr2 variable has been changed and its value is = bptr = (int ptr) <br />
<br />
// Copy from unmanged memory back to array<br />
Marshal.Copy(ptr2, buffer, 0, 10);<br />
<br />
// Free memory, or else we will leak it<br />
Marshal.FreeHGlobal(ptr);<br />
Marshal.FreeHGlobal(ptr2);<br />

TJoe6-Sep-07 2:13

6-Sep-07 2:13

Do you have access to the ActiveX source code? Or is it publicly available? If you have access, could you post examples of PutData and GetData. If it's publicly available, could you please provide a link.

If GetData is updating bptr2 so that it has the same value as bptr, then I would assume that PutData simply stored the long* that was passed in (instead of copying it). Then GetData is simply passing out the same long*. If this is the case then you do not need to allocate ptr2, because GetData does not required you to pass in a pre-allocated buffer.

This really depends on how the OCX methods are written and you would need a full understanding of how they work to properly use them. For example, if the PutData does in fact save the long* that was passed in, then the code below would cause access violations:

// Create buffer
Int32[] buffer = new Int32[10];
buffer[5] = 1;

// Allocate and copy to unmanaged memory
IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)) * 10);
Marshal.Copy(buffer, 0, ptr, 10);

// **** Need to add this, otherwise c# complains about not being able to convert IntPtr to int
int bptr = (int)ptr;
ocx.PutData(ref bptr, Marshal.SizeOf(typeof(Int32)) * 10);

// Change buffer, so we can see that the ptr has restored the
// old value
buffer[5] = 2;

// Free memory, or else we will leak it
Marshal.FreeHGlobal(ptr);

// ... Somewhere else in code


// **** Allocate another are to retrieve data
IntPtr ptr2 = IntPtr.Zero;
int bptr2 = (int)ptr2;

ocx.GetData(ref bptr2);

// Copy from unmanged memory back to array
Marshal.Copy(ptr2, buffer, 0, 10);

In the code above, the long* that was cached is freed and then is accessed later. If you are only using the OCX in a serial fashion like your example, then it would be fine.

Let me know if this makes sense.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Paolo Vernazza6-Sep-07 4:33

Paolo Vernazza

6-Sep-07 4:33

No, I haven't access to the activeX source code, but the activeX it is freely available at http://www.kolbasoft.com/

I put the test projects (c# and c++), the link to the activeX and a a few notes in www.vernazza.org/Vecad.zip

I agree with you, it seems that GetData is passing out the long* that I passed it before instead of the data pointed, but I can't understand why it works while I call that function from c++ , and it doesn't when I call it from c#!

TJoe6-Sep-07 5:08

How to limit maximum size of other windows?

6-Sep-07 5:08

You may want to use AllocCoTaskMem[^] instead (and it's associated free method), but I don't think that is your problem.

Looking at the put code:

IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)) * 10);
Marshal.Copy(buffer, 0, ptr, 10);
int bptr = (int)ptr;
axVecad1.PutExData(ref bptr, 10 * 4);

After the first line, ptr points to the allocated block of memory. The array is then copied to the allocated block. Next ptr is cast to an int, so bptr now holds the correct address to the buffer. Now, when passing in the address to the PutExData, the address of the bptr is passed in (ref bptr). What you really want to pass in is the value of bptr. So really you are passing in a pointer to bptr which has a pointer to the actual data (so a pointer to a pointer).

Basically, the signature for the PutExData should have the first parameter as an "IntPtr", not as a "ref Int32". I don't think there is a way to properly pass in the IntPtr address when the signature has the ref value there. Because you would need to create an Int32 value at the same location as the allocated buffer.

I realize that VS generated the signature of the method for you (more specifically, aximp.exe generates it). The best work-around (short of hand-writing all the code you need) I found was here[^]. Be sure to read the whole thread, he talks about activeX controls later in the thread.

Hopefully this helps.

UPDATE: Actually, it looks like aximp.exe can generate C# source code now, so that would probably be your best option.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Trickster-SWE5-Sep-07 6:33

Trickster-SWE

5-Sep-07 6:33

I would like to create a sidebar type application that sits on the right side of the client area. This application will always be executing, and I want it to always be visible.

Is there any way of controlling _other_ windows so that the won't maximise or be resized over/under that application? Optimally I would like another window to maximize to the full screen _except_ for the right X pixels where my sidebar application is residing.

Always on top will fix the "always visible" parameter, but using this other windows will be hidden behind it..

Preferrably I would like to set a registry value or such setting max size, but the next best case is to do this programmatically in my app.

Would really appreciate an answer!

Best regards

// T

Re: How to limit maximum size of other windows?

TJoe5-Sep-07 8:06