[triangulator]

Hi there, currently I'm creating a new sub-window once, in the body of the main window constructor:

PopUp hey = new PopUp();

However, for my needs, this needs to be done in another function along with some other things; more importantly, this function has to be able to create several different sub-windows(e.g. PopUp, HelpWindow, EnterSomeInfo, etc.). I tried this:

        public CreateWindow( Form which)
        {
            which frm = new which();
//....

but I get

Quote

The type or namespace 'which' could not be found. Are you missing a using directive or an assembly reference?

I followed these two links:
http://en.csharp-onl...embly_reference
http://blogs.msdn.co.../29/123028.aspx
but they didn't help me much as I need 'which' to be able to refer to several different forms.
Changing

public CreateWindow( Form which)

to

public CreateWindow( class which)

or

public CreateWindow( object which)

also throws similar errors. How can I pass a class(or rather, form) as an argument of a function?

[tlhIn`toq]

Quote

        public CreateWindow( Form which)
        {
            which frm = new which();
//....

You need to STOP. And then read (or re-read) your textbook.

You are WAY lost. You're not going to be able to build anything until you understand the foundation concepts.

"which" is the instance of a form that is being passed into your CreateWindow method.

Unless you have defined a class that is *also* called which, you are trying to assign your existing instance to something that doesn't exist.

None of this makes any sense for several reasons.
1 - if you are passing in an instance of a form then why would you immediately replace it with a new form of some type
2 - you are trying to assign it to a type that doesn't exist.

Look in my signature block. There are links to tutorials for classes and objects. They might help. But honestly, you need to back up at least 2 chapters in your book and re-work those lessons until you fully comprehend the material. Don't move forward just because you somehow got something working. If you don't actually understand it, then don't move forward.

---

My standard beginner resources post - Updated JAN 2013

---

Plan your study route:
There are three routes people seem to take when learning programming.

• Just start trying to create programs
  
• Start taking apart other programs and try to figure out the language by reverse engineering
  
• Follow a guided learning course (school or self-teaching books)

For the life of me I can't figure out why people try 1 & 2. I strongly suggest taking the guided learning approach. Those book authors go in a certain order for a reason: They know what they're doing and they know the best order to learn the materials.

• First learn the language by working 2-5 "Learn C# in 30 days" type books cover to cover.
  
• Do a dozen on-line tutorial projects where you build what you're told to build, the way you are told to build it WITH AN EXPLANATION OF WHY so you can learn.
  
• Learn to plan before you type.
  
• THEN you start designing software with a purpose.

I don't learn from reading books: I learn by doing.

Spoiler

Total honesty here: That is either B.S., you haven't really tried, or this is the wrong career field for you so bail out now.
You can try to learn C# by dismantling snippets and googling terms - basically you can take a hit-n-miss, shotgun approach. But honestly, just typing away and seeing what pops up in Intellisense is going to make your self-education take 20 years. You can learn by trying to reverse engineer the language through banging on the keyboard experimentation - or you can learn by doing the tutorials and following a good "How to learn C#" book. There are so many great "How do I build my first application" tutorials on the web... There are dozens of "Learn C# in 21 days", "My first C# program" type books at your local book seller or even public library.

I'll tell you from experience that just fumbling around in the dark and trying to teach yourself with no guidance doesn't work. Its like stumbling across a Harrier Jump Jet and trying to teach yourself how to fly with no background in piloting: You simply lack any groundwork to start from. How can you lay out your own training course if you don't already know the material? Would you go to a university where the teacher says "I don't know any of this but we'll fumble through it together?"

Newbie/Rookie said:

I have little/no programming experience but I need to write a program by Friday that does XYZ.

Spoiler

You need to start there. I can't say "I have little experience in speaking Russian, but I have been assigned to write a mystery novel in Russian. Can you help me?"

We can help you by saying "First learn basic programming and the language of C#. Then take on assignments." Could someone here write this program for you? Sure. Could someone here map out all the processes you need to follow and do the Software Design part of this in the slim hope you could code it from there? Sure. But we don't volunteer to do the job that you're either getting paid for, or getting a grade for. You may want to read this.

For now, just work on the lessons. Do a self-teaching book from cover to cover. Then consider writing a program.

Don't try to create a useful working program to fit a need of yours (or a for-pay contract) as your introduction to coding project. When you are learning to code you don't know enough to code a program, let alone know how to engineer the architecture of a program. It would be like saying "I don't know how to read sheet music, or play an instrument. I think I'll write a 3 act opera as my first learning experience."

I don't say this to be mean. We've seen lots of new coders take this approach and we know it doesn't work. Trying to design your own programs before you understand the basics of the code language you've chosen just leads to problems, frustrations, and 'swiss-cheese' education (lots of holes).

---

Resources, references and suggestions for new programmers.

---

Spoiler

Some of the tutorials below may not be in your chosen program language {C#, Java etc.} But the conceptual stuff of classes, object oriented design, events etc. are not language specific and should give you enough guidance in theory of program development for you to be able to look-up specific code example in your chosen coding language.


Free resources:

Spoiler

• We have a tutorials section and a Learning C# series of articles.
  
• MSDN Press - Free books
  
• There are numbers How-To videos on YouTube. Try this search: C# lesson 1

Articles that I constantly send people to - Good place to start.

• Learning C# series
  
• Understanding the common errors
  
• Bulding an application - Part 1
  
• Building an application - Part 2
  
• Quick and easy custom events
  
• Passing values between forms/classes ('How do I get Form1 to talk to Form1?')
  
• Separating data from GUI - PLUS - serializing the data to XML

Further debugging of your own code so you aren't asking others to do it for you:

Spoiler

• Debugging tutorial
  
• Debugging tips
  
• Debugging in detail
  
• Great debugging tips
  
• It still doesn't work, article

Writing a text file is always one of the first things people want to do, in order to store data like high-scores, preferences and so on.
Writing a text file tutorial.
Reading a text file tutorial.
.Split()ing a string

The stages of asking for homework help on a forum


Thread with example WPF window using binding and a UserControl with properties

Beginner:

• C# learning series right here on Dream in code
  
• MSDN Framework Development Guide
  
• C# Reading list by Eric Lipert
  
• C# Fundamentals: Development for absolute beginners (video series)
  
• Build a Program Now! in Visual C# by Microsoft Press, ISBN 0-7356-2542-5 is a terrific book that has you build a Windows Forms application, a WPF app, a database application, your own web browser.

Martyr2's mega project ideas list is a great place to start on developmental projectst that you can learn from; rather than trying to make something complex like a game as a self-teaching tool {that never works for anyone}

• Visual Studio Keyboard Shortcuts
  
• D.I.C. C# Resource page Start here
  
• Intro to C# online tutorial then here...
  
• C# control structures then here.
  
• MSDN Beginner Developer video series
  
• MSDN video on OOP principals, making classes, constructors, accessors and method overloading
  
• MSDN Top guideline violations, know what to avoid before you do it.
  
• Design patterns as diagrams

I hate sending people to another site when we have such good tutorials here, but this series shouldn't be overlooked.

• Programming OOP in C# - Part 1
  
• Programming OOP in C# - Part 2
  
• Programming OOP in C# - Part 3
  
• Programming OOP in C# - Part 4
  
• Programming OOP in C# - Part 5

Have you seen the 500+ MSDN Code Samples? They spent a lot of time creating samples and demos. It seems a shame to not use them.



Intermediate:

• OOP design patterns
  
• Microsoft Events (webcasts and podcasts)
  
• WPF version (WPF-MVVM data binding)
  
• Decouple your multi-threaded work from the GUI so forms don't hang
  
• Working with environmental variables
  
• 'Why do we use delegates?' thread
  
• And everyone always wants to connect to a database, right out of the gate so Database tutorials right here on DIC
  
• C# Cookbooks
  
• Are a great place to get good code, broken down by need, written by coding professionals. You can use the code as-is, but take the time to actually study it. These professionals write in a certain style for a reason developed by years of experience and heartache.

Everyone:

• Microsoft Visual Studio Tips, 251 ways to improve your productivity, Microsoft press, ISBN 0-7356-2640-5 Has many, many great, real-world tips that I use all the time.
  
• MSDN C# Developers Center with tutorials
  
• Welcome to Visual Studio
  
• Free editions of Visual Studio 2010
  
• Student editions of Visual Studio

Some of my common tips (some may apply more than others to your specific style):

• Take the extra 3 seconds to rename your controls each time you drag them onto a form. The default names of button1, button2... button54 aren't very helpful. If you rename them right away to something like btnOk, btnCancel, btnSend etc. it helps tremendously when you make the methods for them because they are named after the button by the designer.btnSend_Click(object sender, eventargs e) is a lot easier to maintain than button1_click(object sender, eventargs e)
  
  
• You aren't paying for variable names by the byte. So instead of variables names of a, b, c go ahead and use meaningful names like [font="Courier New"]index, timeOut, row, column and so on. You should avoid 'T' for the timer. Amongst other things 'T' is commonly used throughout C# for Type and this will lead to problems. There are naming guidelines you should follow so your code confirms to industry standards. It makes life much easier on everyone around you, including those of us here to help. If you start using the standards from the beginning you don't have to retrain yourself later.
  You might want to look at some of the naming guidelines. Its a lot easier to start with good habits than to break bad habits later and re-learn.
  
  
  • Guidelines for names
    
  • Naming guidelines
    
  • Design guidelines for classes
  
  
  
• Don't use your GUI objects as your variable. In other words don't keep referencing TextBox4.Text everyplace. TextBox4.Text is not a variable or property. The GUI is on its own thread so as soon as you start doing multi-threading you're screwed because your worker thread can't access the GUI elements. Use properties.
  
  
• Try to avoid having work actually take place in GUI control event handlers. It is better to have the GUI handler call other methods so those methods can be reused and make the code more readable. This is also how you can send parameters rather than use excessive global variables. Get in this habit even if you are using WinForms because WPF works a lot under the idea of "commands" and this will get you working towards that. Think of each gester, control click, menu option etc. as a command to do something such as a command to SAVE. It doesn't matter where the command comes from, all sources should point at the same target to do the actual saving.
  
  Spoiler

  
  

  // All of this different triggering mechinisms call the same single [il]SavePreferences()[/il] method
  
  btnSave(object sender, eventargs e)
  {
      SavePreferences(preferencesPath);
  }
  
  <KeyboardShortcut control+s bound to save>
  <Touchscreen guesture swiping from lowerleft to upperright bound to save>
  
  SaveMenuItem(object sender, eventargs e)
  {
      SavePreferences(@"C:\prefs\test.txt");
  }
  
  SaveContextMenu(object sender, eventargs e)
  {
      SavePreferences();// No parameter method overload
  }
  
  FormMain_Closing(object sender, eventargs e)
  {
      if (IsDirty) SavePreferences();
  }
  

  
  
  
• Don't replace lines of code that don't work. Instead comment them out and put your new attempts below that. This will keep you from re-trying the same ideas over and over. Also, when you come back to us saying "I've tried this 100 different ways and still can't get it", we can actually see what you tried. So often a failed attempt is very very close and just needs a little nudge in the right direction. So if we can say "See what you did in attempt 3... blah blah" it helps a lot
  
  
  Spoiler

  // Try #1 - May 1, 0900hrs
  //    code
  //    code  
  //    code
  // Try #2 - May 2, 1700hrs   Okay, plan B.  What if I do it *this* way
  //    code
  //    code  
  //    code
  // Try #14 - May 3, 0500hrs after 5 cans of RedBull.  Maybe I should get some sleep. I can't think of anything else but this last idea
      code
      code  
      code
  
  

  
  If you are using Visual Studio you can select a block of lines and hit control+k control+c (Kode Comment) to comment it out. control+k control+u (Kode Uncomment) to uncomment a selected block.
  
  
  
• You have to program as if everything breaks, nothing works, the cyberworld is not perfect, the attached hardware is flakey, the network is slow and unreliable, the harddrive is about to fail, every method will return an error and every user will do their best to break your software. Confirm everything. Range check every value. Make no assumptions or presumptions.
  
  
• I strongly suggest installing VMware or some other virtualization technology on your development PC so you can create a couple virtual computers for testing. This would allow you to debug and test inside: WinXP32, XP64, Vista, Win7x32, Win7x64... etc. without having to actually have 5 physical PC's. Visual Studio will let you send the debug directly into one of these virtual machines so you can watch it operate, check its variables, see the crashes and so on just as if it were debugging on your real machine.
  
  
• This can't be stressed enough in today's world of cell phone messaging:
  Don't use txt/sms/leet/T9 speak like: dnt no wut i m do-n, coz, al gud, b4, ny1, sum1, u r, and so on like this guy. Its completely disrespectful to the senior coding professionals that volunteer here to mentor you.
  
  
  Spoiler

  dis not b d'hood dawg... You are sitting at a real keyboard with a real monitor, not a cell phone. You are not here texting your high school posse to come to your kegger after their shift at Taco Bell. You are here asking for help from senior coding professionals who graciously donate their valuable time to helping the next generation of coders with their chosen craft. Please try to show them, yourself and the industry some respect by writing at least at an eighth grade level. (IE: English not ebonics or SMS, real words, punctuation and so on). If you can't take your own problem/question seriously enough to write like an adult, then why would you expect anyone else to take it seriously?
  
  When you write a post you are presenting yourself. Your writing style is all you have to show others who you are and what you stand for. When I see posts filled with lack of capitalization, SMS text like 'Urself', lack of punctuation and so on; what I see is someone who just doesn't care to make even an eighth grade presentation of themselves. I also see that you feel we are not worth the effort. Posts that look like this show that you don't feel the person you are talking to is worth speaking to as an adult. If you show this level of contempt or apathy towards someone you are asking for help how can you expect to be taken seriously or expect to receive that expert's fullest attention and time to help you?

[lordofduct]

you want to reference a Class, then create an instance based off the Class you have referenced. Dynamically constructing objects with out exact knowledge of the type it will be.

This is called reflection, and can be done with the Activator class:

public Form CreateForm(Type classType)
{
     if(!typeof(Form).IsAssignableFrom(classType)) throw new ArgumentException("Supplied type must inherit from Form");

     return System.Activator.CreateInstance(classType) as Form;
}

Note CreateInstance does allow for an object array to pass in parameters if you need to with a constructor that requires parameters.





Now that I've answered your question. Why do you need this? This isn't really considered an appropriate method for creating objects, but can be useful if your design requires it. But before implementing it you need to ask yourself if your design is the right design int he first place.

[triangulator]

Well, I'm not that novice. FWIW I've already written a program (~4k lines long) that works. Now that I read your explaination I do understand the siliness of my try.
I needn't 'which' to be an instance of a form. Rather, I've been trying to create a shorthand of this thing:

        public createWindow( int which)
        {
            switch (which)
            {
                case 1: PopUp mywindow = new PopUp(); break;
                case 2: HelpWindow mywindow = new HelpWindow(); break;
                case 3: EntersomeInfo mywindow = new EntersomeInfo(); break;
                case 4: Options mywindow = new Options(); break;
//...
            }
//...

Do you know how could this be done? Thanks in advance.

update: I was answered while replying.

Quote

Now that I've answered your question. Why do you need this? This isn't really considered an appropriate method for creating objects, but can be useful if your design requires it. But before implementing it you need to ask yourself if your design is the right design int he first place.

Well, the main window of the program is supposed to work with one out of several different classes at a time, each of which inherits from an abstract class. And each class requires a set of subwindows that would appear in the main window(the main window is something like MDI).
The program then needs to be able to switch between instances the classes it is working with, destroying one and creating another in its place.
Now, the calling of a subwindow requires some settings that go along with it, which are the same. So instead of

PopUp mywindow = new PopUp();
mywindow.settings = whatever;
mywindow.settings2 = whatever;
mywindow.settings3 = whatever;
HelpWindow mywindow2 = new HelpWindow();
mywindow2.settings = whatever;
mywindow2.settings2 = whatever;
mywindow2.settings3 = whatever;
EntersomeInfo mywindow3 = new EntersomeInfo();
mywindow3.settings = whatever;
mywindow3.settings2 = whatever;
mywindow3.settings3 = whatever;
Options mywindow4 = new Options();
mywindow4.settings = whatever;
mywindow4.settings2 = whatever;
mywindow4.settings3 = whatever;
// five or so more windows to come

I was trying to do this:

mywindow = createWindow(PopUp);
mywindow2 = createWindow(HelpWindow);
mywindow3 = createWindow(EnterSomeInfo);
mywindow4 = createWindow(Options);
// five or so more windows to come

[lordofduct]

Activator should do the job.

I'm not saying your design is bad. I actually have a similarish thing going on in our product at work. I call it my 'FormManager' which can receive keys for the kind of form to be opened. I then have XML that defines the entries for a menu (there's tons, a big piece of software), and each entry references the key it deals with (I say key because the key contains both the form to be opened, but also other info to go with it... depending on the form). Then I have multiple menu systems that can consume the XML, this way the user can select from multiple menu styles.

The keys also play other roles, such as defining tasks that consist of going through multiple forms in succession in a specific order.