C# Discussion Boards - CodeProject

Re: highlighting text in a combo box with the mouse

26-Jan-04 10:00

It depends on the ComboBox.DropDownStyle style. If you're using ComboBoxStyle.DropDown, you can select and enter new text. If you use ComboBoxStyle.DropDownList then only the list items in that ComboBox can be select and, hence, there is no need to highlight certain text. This behavior is defined by the Combo Box Common Control which the .NET ComboBox class encapsulates, hence the behavior is the same for native Combo Box controls in Win32 applications. This is not a bug.

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-----END GEEK CODE BLOCK-----

Anonymous26-Jan-04 10:08

Anonymous

26-Jan-04 10:08

Actually, you can't select the text even if you are using DropDown instead of DropDownList. You can edit the text and enter new text, but you can't highlight the text with the mouse like you normally can in an edit box. You can use shift and the arrow keys to highlight text, but holding down the mouse button and moving the mouse will not work. I've read on the internet that this is a bug.

Does any one know of any combobox controls on the internet that might fix this bug, or would the only way to get around it be capturing the mouse events and trying to do it on my own?

Thanks,
Blake

Re: highlighting text in a combo box with the mouse

Heath Stewart26-Jan-04 10:25

Re: highlighting text in a combo box with the mouse

26-Jan-04 10:25

Works in .NET 1.1, but I did notice it doesn't work in .NET 1.0. Never noticed that. If you can, upgrade your code base to 1.1. It does contain enhancements and bug fixes (like for this bug! Smile | :)

) after all. If not, you could implement this using the mouse events or overriding WndProc in a derived class and handling the notification messages, though doing all that should be exposed through mouse events and managed methods already (at least in this case). Note that creating such a work around will probably break the correct behavior when run under .NET 1.1.

blakeb_126-Jan-04 10:36

blakeb_1

26-Jan-04 10:36

Okay, thanks!

Blake

Taking advantage of other langs in .NET

bneacetp26-Jan-04 9:24

bneacetp

26-Jan-04 9:24

Let's say that I created a DLL of managed code in VB.NET and wanted to use that in my C# project. What code would allow me to "import" the code from the file for use in my C# projects?

Thanks in advance! Smile | :)

Happy Programming!

WWW::CodeProject::BNEACETP

Heath Stewart26-Jan-04 9:57

26-Jan-04 9:57

All managed code written from a language which targets the CLR compiles to Intermediate Languages, or IL. Assemblies are language-independent. Just add a reference to this managed assembly in your C# project, just like you reference System.* assemblies (almost all written in C#) in VB.NET. As far as assemblies are concerned, the source language in which they were written does not matter (although some languages support more features of Microsoft IL (MSIL) than others).

bneacetp26-Jan-04 10:41

bneacetp

26-Jan-04 10:41

Thanks for the help! Smile | :)

Happy Programming!

WWW::CodeProject::BNEACETP

Guillermo Rivero26-Jan-04 10:47

Guillermo Rivero

26-Jan-04 10:47

In your opinion, what's the best language to develop .NET applications ??

Free your mind...

Heath Stewart26-Jan-04 11:17

26-Jan-04 11:17

IMO, C#. It was, after all, written from the ground-up for the .NET Framework and supports almost every feature of MSIL based on what I've read in the ECMA standard for the Common Language Infrastructure (CLI). It also offers a syntax similar to many powerful languages like C++, Java, and Perl which makes learning and knowing other languages easier.

How to return/store references on objects

Guillermo Rivero26-Jan-04 11:49

Guillermo Rivero

26-Jan-04 11:49

Thanks.

Free your mind...

Anonymous26-Jan-04 8:42

Anonymous

26-Jan-04 8:42

All is in the title:

I want to store and return references to objects.

How can I do that?

Thanks

Not Active26-Jan-04 9:52

Not Active

26-Jan-04 9:52

Foo(ref object oMyObj)

Bar MyBar = new Bar();

Foo(ref MyBar)

Heath Stewart26-Jan-04 9:55

26-Jan-04 9:55

Why are you ref'ing an object? It's already a reference type. This is really only necessary for value types.

Not Active26-Jan-04 10:56

Not Active

26-Jan-04 10:56

Typing to fast Blush | :O

and doing to many things at once Roll eyes | :rolleyes:

Haste makes waste I guess

Jörgen Sigvardsson26-Jan-04 11:14

Jörgen Sigvardsson

26-Jan-04 11:14

Because it's not the same kind of reference...? A ref parameter behaves like a reference in C++ - you can modify what it refers to.

static void Foo(ref string str) {
    str = "Yo";
}
 
static void Main(string[] args)
{
    string s = null;
    Foo(ref s);
    Console.WriteLine(s); // Will print "Yo" and not null
}

--
<british-accent>Pass the jam, would you?

Not Active26-Jan-04 11:18

Not Active

26-Jan-04 11:18

Yeah but I misread the original question. He wanted to store and retrieve not pass the object to a method.

Jörgen Sigvardsson26-Jan-04 11:20

Jörgen Sigvardsson

26-Jan-04 11:20

Yeah I saw that later in Heath's response. Anyhow, Heath was generalizing a bit too much on references. They are handy at times just as out. Smile | :)

--
<british-accent>Pass the jam, would you?

Heath Stewart26-Jan-04 11:41

26-Jan-04 11:41

For strings, yes, because they are immutable and handled a little differently. I agree that ref and out are handy even in managed code (they are often necessary when P/Invoking native methods, sometimes even with reference types (like for pointer pointers)), but in the case discussed here they are not.

Keep in mind, though, that objects do not require this - only value types and strings (guess I should'be mentioned that too, but at the time I didn't think about it). Take this little example:

using System;
 
public class Test 
{
  public static void Main()
  {
    string s = string.Empty;
    Console.WriteLine(s);
 
    Foo(s);
    Console.WriteLine(s);
 
    Test t = new Test();
    Console.WriteLine(t.s);
 
    Foo(t);
    Console.WriteLine(t.s);
  }
  private static void Foo(string s)
  {
    s = "Testing";
  }
  private static void Foo(Test t)
  {
    t.s = "Testing";
  }
 
  public string s;
 
  public Test()
  {
    s = "This is a test";
  }
}

The output would be:

 
 
This is a test
Testing

Jörgen Sigvardsson26-Jan-04 13:41

Jörgen Sigvardsson

26-Jan-04 13:41

I see what you mean. Basically you're just creating a handle (the "reference"), in this case Test. Bear in mind that I do COM on a daily basis. [out] is God. Wink | ;)

--
Try walking in my shoes. You stumble in my footsteps.

Heath Stewart26-Jan-04 9:53

CEMAPI use in C# :confused:

26-Jan-04 9:53

Properties and fields, a basic element of objects:

public class MyClass
{
  private object o1;
  private object o2;
  public MyClass()
  {
  }
  public object O1
  {
    get { return this.o1; }
    set { this.o1 = value; }
  }
  public object O2
  {
    get { return this.o2; }
    set { this.o2 = value; }
  }
}

Can you use fields instead if they are public, but properties are recommended because you can check the value before assigning them to your private fields ("store").

You should read the topics discussed in the .NET Framework SDK as well as vast collection of articles here on CodeProject for examples.

If you're talking about serialization, see http://msdn.microsoft.com/library/en-us/cpguide/html/cpovrserializingobjects.asp[^]. This gives an overview of serialiation as well as advanced topics and many examples using binary and SOAP serialization, as well as the more basic XML Serialization (which doesn't handle everything that true serialization, but is good to use in many cases such as storing configuration options and application state. There are several articles here on CodeProject that discuss those. Just do a search for serialiation.

camasmartin26-Jan-04 8:08

camasmartin

26-Jan-04 8:08

I am trying to develop a program for the PocketPC in C#. It requires the use of cdmapi which only is available in the SDK as cemapi.h and cemapi.lib for C++. I really don't want to do this in C++.

How can I use/access/import/convert/??? the available library for use in C#.

Thank in advance for the advice

camasmartin
hobby programmer

Re: CEMAPI use in C# :confused:

Heath Stewart26-Jan-04 9:47