passing data between forms - C# Discussion Boards

Matt U.31-Aug-12 9:59

31-Aug-12 9:59

In the past, I had honestly never really been too great with inheritance and such. I've used interfaces before but never "properly" I guess you would say. So today, in order to grasp the concept a little more, I decided to experiment with it a bit. I created a Class Library with components I can use to create the structure of a "quiz." The project is simply called "QuizLib." Now, the functionality works just as I had planned. But I would like to know if I went about it the correct way:

Interfaces

IQuiz - Quiz interface; contains information about the quiz (title, subtitle, etc.)
    * string Title; - The title of the quiz
    * string SubTitle; - The subtitle of the quiz
    * List<iquestion> Questions; - A collection of questions which are part of the quiz

    * void AddQuestion(IQuestion question);
    * void RemoveQuestion(IQuestion question);

IQuestion - Question interface; contains information about questions which are part of the quiz (IQuiz)
    * string QuestionText; - The text for the question (e.g. Is CodeProject.com the best?!)
    * int Points; - The amount of points the question is worth

IAnswer - Answer interface; contains information about an individual answer for an IQuestion
    * string AnswerText; - The answer's text (what will be displayed when you render the question with answers - e.g. "Yes", e.g. "No")
    * bool IsCorrect; - Is the answer a correct answer (this is only used in Multiple Choice questions and True/False questions)

And then I have 2 classes which implement the IQuestion interface. And I have 2 classes which implement the IAnswer interface.

class MultipleChoiceQuestion : IQuestion ...... class TrueFalseQuestion : IQuestion

class MultipleChoiceAnswer : IAnswer ...... class TrueFalseAnswer : IAnswer

For MultipleChoiceQuestion, there is no limit on how many answers the question can have. The MultipleChoiceQuestion class adds a "HasOneAnswer" field, which determines whether or not only ONE answer can be correct, or if the user must select more than one in order to correctly answer the question. For TrueFalseQuestion, the List<ianswer> field is auto-generated by the class, since "True" and "False" are the only 2 options.

I hope this makes sense to everyone. Haha. I'm just trying to find out if I'm getting the concept fairly well. Or what I may need to do in order to improve in this topic.

Again, it works as expected. I can easily extend the code to support various question and answer types. That seems to be the basic concept. But still, I wanted to ask. Smile | :)

djj55: Nice but may have a permission problem
Pete O'Hanlon: He has my permission to run it.

Re: Experimentation - Would Like Feedback

SledgeHammer0131-Aug-12 10:52

SledgeHammer01

31-Aug-12 10:52

Seems silly to split up IQuestion and IAnswer. You're never going to have a MultipleChoiceQuestion paired up to a TrueFalseAnswer for example, so that should be a single object IMO. An IQuestion+Answer type object. Even if you kept your design, I see no way of actually mapping a question to an answer.

Re: Experimentation - Would Like Feedback

ekolis31-Aug-12 11:26

ekolis

31-Aug-12 11:26

I'd recommend using a generic

List<IQuestion>

for the questions instead of a plain old List. That way you don't have to worry about casting the questions to IQuestion, or having someone add something that's not an IQuestion to the list!

Re: Experimentation - Would Like Feedback

Ravi Bhavnani31-Aug-12 12:36

Ravi Bhavnani

31-Aug-12 12:36

Since IQuiz has methods to add/remove questions, its Questions property should be a get-only IEnumerable of IQuestion objects instead of a List.

I would recommend separating the question/answer definitions (which are reference, read-only data) from a user's responses (which can be modified). Will reply with another post over the weekend.

/ravi

My new year resolution: 2048 x 1536
Home | Articles | My .NET bits | Freeware
ravib(at)ravib(dot)com

Re: Experimentation - Would Like Feedback

OriginalGriff1-Sep-12 1:53

OriginalGriff

1-Sep-12 1:53

To add to the previous answers, I would not use an interface for this - I would use an abstract class instead. The reasoning is that some of your logic will be common to all questions/answers in the form of the Questions enumeration (which should be a get only property returning a List<iquestion> as Ravi says) but it should return a copy of the questions list, not the list itself. Using an abstract class allows this to be in the base, an Interface doesn't so you have to rely on the implementor getting this right each time.

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Re: Experimentation - Would Like Feedback

Matt U.6-Sep-12 7:29

Matt U.

6-Sep-12 7:29

I appreciate all the input. I will be taking this all into consideration as I go. It's just a learning project, nothing I planned to take anywhere. So this will all give me a fair amount of things I can learn in order to improve. Thanks!

djj55: Nice but may have a permission problem
Pete O'Hanlon: He has my permission to run it.

Re: Experimentation - Would Like Feedback

OriginalGriff6-Sep-12 7:58

OriginalGriff

6-Sep-12 7:58

You're welcome!

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

passing data between forms

mamoony31-Aug-12 8:53

mamoony

31-Aug-12 8:53

Hi,

I have a dll class and from here I am calling a form. I am able to send data from the dll class to the form. But how I am going to get data back from the form to the dll class? I wsed the same code but it is not working backward.

frmLogin login = new frmLogin();
           
            login.Type = type;
            login.Username = username;
            login.Password = password;
            login.Group = group;
            
            login.ShowDialog();

Thanks in advance,
Sai

Re: passing data between forms

Richard Andrew x6431-Aug-12 9:18

Richard Andrew x64

31-Aug-12 9:18

Why can't you simply reverse the assignments you have?

login.ShowDialog();

username = login.Username;
password = login.Password;

etc....

The difficult we do right away...
...the impossible takes slightly longer.

Re: passing data between forms

OriginalGriff31-Aug-12 9:21

OriginalGriff

31-Aug-12 9:21

Create a property (or several) in the Form and read it back from the instance once ShowDialog returns - it won't until the user closes the form, so read the data at that point.

frmLogin login = new frmLogin();
login.Type = type;
login.Username = username;
login.Password = password;
login.Group = group;

login.ShowDialog();

type = login.Type;
username = login.Username;
password = login.Password;
group = login.Group;

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Re: passing data between forms

mamoony31-Aug-12 10:08

mamoony

31-Aug-12 10:08

What I did....
In Class 1

if (login.ShowDialog()== DialogResult.OK)
            {
                ans= login.Result;
            }

In form 1

public int Result
       {
           get;
           set;
       }

Result = value;
            this.DialogResult = DialogResult.OK;

Thnks a lot all,
Sai

Re: passing data between forms

OriginalGriff31-Aug-12 21:09

OriginalGriff

31-Aug-12 21:09

That'll do it!
Nice one - well done.

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Re: passing data between forms

BillWoodruff3-Sep-12 15:59

BillWoodruff

3-Sep-12 15:59

I can't make any connection between the code you show here, and any other post on this thread:

This code is not going to compile:

1. the variable 'ans is never declared, or used, just assigned to; will not compile.

2. the variable 'value is never declared: Result = value; will not compile.

3. the statement: "this.DialogResult = DialogResult.OK;" makes no sense unless you have a Form1 scoped variable with the name 'DialogResult declared, and, you should not use variable names identical to Operator names since that way lies utter code confusion. And why would you need a Form1 scoped variable of this type in the first place ?

This is a case where posting code-fragments means no meaningful response is possible.

best, Bill

"If you shoot at mimes, should you use a silencer ?" Stephen Wright

Re: passing data between forms

mamoony10-Sep-12 10:06

mamoony

10-Sep-12 10:06

It compiled and worked.

Thanks,
Sai

Delete From XML File

Kevin Marois31-Aug-12 8:47

Kevin Marois

31-Aug-12 8:47

I have this XML file

<?xml version="1.0" encoding="utf-8"?>
<Contacts>
  <Contact>
    <ContactId>0</ContactId>
    <Prefix>
    </Prefix>
    <FirstName>Kevin</FirstName>
    <MiddleName>Marois</MiddleName>
    <LastName>Brian</LastName>
    <Suffix>
    </Suffix>
    <Birthday>1965-10-11</Birthday>
    <Title>Senior Software Engineer</Title>
    <Comments>has 25 years of development experience</Comments>
  </Contact>
  <Contact>
    <ContactId>1</ContactId>
    <Prefix>Dr.</Prefix>
    <FirstName>Henry</FirstName>
    <MiddleName>DeCarlo</MiddleName>
    <LastName>G</LastName>
    <Suffix>III</Suffix>
    <Birthday>1965-10-11</Birthday>
    <Title>Oral Surgeon</Title>
    <Comments>His office is over on 23rd street</Comments>
  </Contact>
  <Contact>
    <ContactId>2</ContactId>
    <Prefix>
    </Prefix>
    <FirstName>Mattew</FirstName>
    <MiddleName>Damon</MiddleName>
    <LastName>Paige </LastName>
    <Suffix>
    </Suffix>
    <Birthday>1970-10-08</Birthday>
    <Title>Actor</Title>
    <Comments>Excellent actor</Comments>
  </Contact>
</Contacts>

I want to delete a contact using the ContactId. So far I have this:

public void DeleteContact(int ContactId)
{
    ensureFileExists();
    XmlDocument doc = new XmlDocument();
    doc.Load(XMLFile);
    var path = "/contacts/contact[ContactId=" + ContactId + "]";
    XmlNode node = doc.SelectSingleNode(path);
    node.ParentNode.RemoveChild(node);  

    doc.Save(XMLFile);
}

But the node is coming back null. How do I delete the contact? What's wrong here?

Thanks

If it's not broken, fix it until it is

Re: Delete From XML File

PIEBALDconsult31-Aug-12 9:40

PIEBALDconsult

31-Aug-12 9:40

Ahem... case sensitivity... Java | [Coffee]

Re: Delete From XML File

Kevin Marois31-Aug-12 9:52

Kevin Marois

31-Aug-12 9:52

That did it. Thanks

If it's not broken, fix it until it is

Re: Delete From XML File

PIEBALDconsult31-Aug-12 11:20

PIEBALDconsult

31-Aug-12 11:20

And if that's your actual date of birth, then you're about two months older than me. Jig | [Dance]

Re: Delete From XML File

AmitGajjar31-Aug-12 23:27

AmitGajjar

31-Aug-12 23:27

you catch it quickly so 5+

Thanks
-Amit Gajjar (MinterProject)

To show the properties page of a file and navigate to a tab

John T.Emmatty31-Aug-12 4:03

John T.Emmatty

31-Aug-12 4:03

In my software i need to show the property dialog of a file and navigate to a specific tab in that property dialog? please tell me how to acheive this using c#?

or Is it possible to replace the default property dialog with a custom one?

Re: To show the properties page of a file and navigate to a tab

Shameel31-Aug-12 4:56

Shameel

31-Aug-12 4:56

Use the ShellExecuteEx Win32 API to achieve this.

using System.Runtime.InteropServices;

[DllImport("shell32.dll", CharSet = CharSet.Auto)]
static extern bool ShellExecuteEx(ref SHELLEXECUTEINFO lpExecInfo);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct SHELLEXECUTEINFO
{
    public int cbSize;
    public uint fMask;
    public IntPtr hwnd;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpVerb;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpFile;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpParameters;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpDirectory;
    public int nShow;
    public IntPtr hInstApp;
    public IntPtr lpIDList;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpClass;
    public IntPtr hkeyClass;
    public uint dwHotKey;
    public IntPtr hIcon;
    public IntPtr hProcess;
}

private const int SW_SHOW = 5;
private const uint SEE_MASK_INVOKEIDLIST = 12;
public bool ShowFilePropertiesDialog(string fileName)
{
    SHELLEXECUTEINFO info = new SHELLEXECUTEINFO();
    info.cbSize = System.Runtime.InteropServices.Marshal.SizeOf(info);
    info.lpFile = fileName;
    info.lpVerb = "properties";
    info.fMask = SEE_MASK_INVOKEIDLIST;
    info.nShow = SW_SHOW;
    return ShellExecuteEx(ref info);
}

And then use the method like this:

ShowFilePropertiesDialog(@"C:\hello.txt");

Re: To show the properties page of a file and navigate to a tab

John T.Emmatty31-Aug-12 5:08

John T.Emmatty

31-Aug-12 5:08

Thanks.but this would only display the property dialog, i need a way to navigate into one of tabs inside the property dialog.

Re: To show the properties page of a file and navigate to a tab

Shameel31-Aug-12 5:11

Shameel

31-Aug-12 5:11

How about using SendKeys[^] to send as many Control+Tab characters as required?

.Net C# GUI dll will use in VB6 (Not user control)

mamoony31-Aug-12 3:52

mamoony

31-Aug-12 3:52

Hi,

I want to create a .Net Dll in c# which will have a GUI. I need to use this in a VB6 application. Is this possible?

I know how to create a class dll in C# and use it in VB6 also I can create an User Control in C# and used it in VB6 form.

What I want is the VB6 will call a dll (login screen) and the C# GUI will run and give back a yes/no result.

Thanks,
Sai

Re: .Net C# GUI dll will use in VB6 (Not user control)

Shameel31-Aug-12 4:47

Shameel

31-Aug-12 4:47

This[^] article discusses using .NET user control in VB6.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.