Develop Reference

How to add/remove items from a list from a different form?

Say I have a list called listOfFruits in my main form. In a second form I've made I want the user to be able to remove items from that list to a second list called removedFruits. Currently I know I can access these lists in my second form simply passing them as parameters in the form constructor. However c# can't do pointers (correct?) so how can I effect the main form's copy of these lists from my second form? Because currently any changes to those lists in my second form don't effect the main form's original copy of the lists. If I were to remove 5 fruits from the listOfFruits passed to my second form then after finishing my work the main form would still still have a full listOfFruits and an empty removedFruits. Is there a simple fix to this? Maybe a get/set or a way to add/remove items from the original lists from the second form? Maybe the answer is in some sort of accessor stuff?
EDIT: To clarify; I want to add to one list, and remove from another. Not add/remove to the same list. Not sure if this matters entirely but I figured I'd be specific here in case it does.
EDIT2: I think the issue is I'm copying the original list from the first form and not editing it directly. Can someone fix my code so I can access the original list from my second form instead of making a copy of the list?
public partial class ListSelector : Form
{
private string windowName = Form1.typeOfModuleAdded;
public List<IOModule> innerIOList;
IOModule cardAdded = null;
public ListSelector(List<IOModule> cardList)
{
this.Text = windowName;
innerIOList = cardList;
InitializeComponent();
InitializeList();
}
private void InitializeList()
{
if (windowName == "Drive")
{
string[] listDrives = { "ACS880", "test" };
listBox1.Items.AddRange(listDrives);
}
else if (windowName == "IOBlock")
{
if (!innerIOList.Any())
{
MessageBox.Show("No cards loaded! Please import cards from IO List.", "Error Empty Data", MessageBoxButtons.OK, MessageBoxIcon.Error);
this.Close();
}
foreach (IOModule card in innerIOList)
{
cardAdded = card;
listBox1.Items.Add(card.name);
}
}
else if (windowName == "Local Card")
{
string[] listLocals = { "1756-EN2T", "test" };
listBox1.Items.AddRange(listLocals);
}
else if (windowName == "Processor")
{
string[] listProcessors = { "1756-L71S", "test" };
listBox1.Items.AddRange(listProcessors);
}
}
private void addBtn_Click(object sender, EventArgs e)
{
if (listBox1.SelectedItem != null)
{
Form1.SetModule(listBox1.SelectedItem.ToString());
Form1.confirmedAdd = true;
this.Close();
}
else if (cardAdded != null)
{
innerIOList.Remove(cardAdded);
}
else
{
MessageBox.Show("No module selected!");
}
}
and here's how I pass the list to that form from my first form:
ListSelector test = new ListSelector(ioList);
test.ShowDialog();
where ListSelector is the name of my second form, and ioList is the list im passing to it.
EDIT3: added more code

"However c# can't do pointers (correct?) so how can I effect the main form's copy of these lists from my second form?"
No, not correct. Any object reference (for instance, of a List<Fruit>) is still very much a pointer to a place in memory, and if you pass the same List<Fruit> object to both Forms, they share the same List.
I don't know why your changes to your listOfFruits don't chow up in your first Form. I would check the following things:
Are you 100% sure you use the same List<Fruit> object in both Forms. (If you create a new List like this: new List<Fruit>(listOfFruits) it is NOT the same List)
Does the first Form have any way of finding out, that the List has changed? Possible using a Timer with recurring checks, or (my favorite) triggering an event when you change something, and subscribe an EventHandler in the first Form to the event.

I assume that you have created a second list in your second form that is filled with the items of the first form's list. Then changes on the second list aren't reflected in the first list. You have to use the same reference of the list.
public Form2(List<Fruit> listOfFruits)
{
this._listOfFruits = listOfFruits;
}
private List<Fruit> _listOfFruits;

Instead using a public field, try to use property and on creating your new ListSelector pass the list to the property.
public partial class ListSelector : Form
{
private string windowName = Form1.typeOfModuleAdded;
private List<IOModule> innerIOList;
IOModule cardAdded = null;
public List<IOModule> CardList
{
get
{
return innerIOList;
}
set
{
innerIOList = value;
InitializeList();
}
}
public ListSelector()
{
this.Text = windowName;
InitializeComponent();
}
When creating your new ListSelector object
ListSelector ls = new ListSelector();
ls.CardList = your mainform list of IOModule here
ls.ShowDialog();

Using XML elements

I have working code that I'd simply like to reference parts of multiple times in other area's of my program, however my problem seems to be with anonymous types (var)
here's a section of my program that loads my XML file
string path = "Data//handling4.meta";
var doc = XDocument.Load(path);
var items = doc.Descendants("HandlingData").Elements("Item");
var query = from x in items
select new
{
HandlingName = (string)x.Element("handlingName"),
HandlingType = (string)x.Element("HandlingType"),
Mass = (decimal?)x.Element("fMass").Attribute("value"),
InitialDragCoeff = (decimal?)x.Element("fInitialDragCoeff").Attribute("value"),
PercentSubmerged = (decimal?)x.Element("fPercentSubmerged").Attribute("value"),
DriveBiasFront = (decimal?)x.Element("fDriveBiasFront").Attribute("value")
};
This code works great, I can also use a foreach loop like this to reference items
foreach(var HandlingName in query)
{
string Names = HandlingName.HandlingName;
}
So my question is, how to reference that to another place in the program? for e.g.
private void button1_Click(object sender, EventArgs e)
{
comboBox1.Items.Add( Names);
}
The above code throws the error 'Names does not exist in the current context'
I need for my comboBox to display each handling name, but it fails because anonymous types cannot be referenced. Am I doing something wrong, or am I just not using the incorrect method? Thanks
Edit: Also to mention that the XML is needing to be referenced in multiple parts of the program, button click even shows the values in a DataGridView for example. If I could make a class to load the XML, then each element in different area's of the program that'd be ideal, rather than loading the hefty block of code each time

the XML is needing to be referenced in multiple parts of the program,
But all your variables are local. You need to store something in a Form fiead or property.
// outside any method:
private List<string> names = new List<string>();
void myLoadMethod()
{
...
foreach(var HandlingName in query)
{
//string Names = HandlingName.HandlingName;
Names.Add(HandlingName.HandlingName);
}
}
private void button1_Click(object sender, EventArgs e)
{
comboBox1.Items.Add( Names);
}

Simple yet frustrating Listbox and Texbox search again

I have spent few days searching everywhere for a solution to this.
This is for C# with Visual Studio 2013 (ya, I am a newbie):
two textboxes (Last name and First Name) and a listbox with 5 names (Higgins M, Higgins J, King J, Tran A, Dempsey S). I set listbox property as sorted.
if I select Higgins J in listbox, then the word Higgins should appear in Last Name textbox and J should appear in First Name textbox.
if I type Higgins in Last Name textbox, Higgins J should be the selected item in listbox (Higgins J will be selected before Higgins M). If I type M in the First Name textbox, the selected item should change from Higgins J to Higgins M.
but....here are the problems that made me decide to create an account here:
If I type Hi or Hig instead of Higgins, it has to stay that way, it does not become Higgins in the textbox. Only the index/highlight in listbox is changed, not the entry in textbox (whatever I type in the textbox stays). I suspect the events that I use are the reason I cannot get this done. Textbox_textchanged and listbox_selectedindexchanged. So whatever I do in one event will automatically triggers the other. I have tried changing the events, but so far the result simply worse. Using: if (LastName_textbox.Text = "") did not help either.
How do I combine Last Name and First Name as one index?
I apologise if this question has appeared or sounded ambiguous. I suppose I do not know how to phrase the search to get something similar to my problem and English is not my first language. Any help is very much appreciated .Thanks.
Here is part of the codes:
using System;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Project
{
public partial class frmContact : Form
{
//declare file to save all contacts
private string fileName = Directory.GetCurrentDirectory() + "\\Contacts.txt";
//create temporary file for updating and deleting contacts
private string newContacts = Directory.GetCurrentDirectory() + "\\newContacts.txt";
public frmContact()
{
InitializeComponent();
}
private void frmContact_Load(object sender, EventArgs e)
{
//create Contacts.txt if it does not exist
if (!File.Exists(fileName))
{
File.Create(fileName).Close();
MessageBox.Show("New " + fileName +" Has Been Created");
tbLast.Select();
}
//if file already exists
else
{
StreamReader readOb = new StreamReader(fileName);
using (readOb)
{
while (!readOb.EndOfStream)
{
string rdLine = readOb.ReadLine(); //read data in file by line
string[] tmpArr = rdLine.Split(',');
lbContact.Items.Add(tmpArr[0] + "," + tmpArr[1]);
}
tbLast.Select();
}
}
}
private void lbContact_SelectedIndexChanged(object sender, EventArgs e)
{
//show details of contact selected in listbox
string findNames = lbContact.GetItemText(lbContact.SelectedItem);
StreamReader obRead = new StreamReader(fileName);
using (obRead)
{
while (!obRead.EndOfStream)
{
string rdLine = obRead.ReadLine();
if (rdLine.StartsWith(findNames))
{
string[] tmpArr = rdLine.Split(',');
tbLast.Text = tmpArr[0];
tbFirst.Text = tmpArr[1].Trim();
tbAddr.Text = tmpArr[2].Trim();
tbSub.Text = tmpArr[3].Trim();
tbPost.Text = tmpArr[4].Trim();
tbEmail.Text = tmpArr[5].Trim();
tbPhone.Text = tmpArr[6].Trim();
tbMob.Text = tmpArr[7].Trim();
}
}
lbContact.SelectedIndex = lbContact.FindString(findNames);
}
}
private void tbLast_TextChanged(object sender, EventArgs e)
{
lbContact.SelectedItem = lbContact.FindString(tbLast.Text);
}

A simple (but kind of ugly solution) would consist in using a boolean value to inform your lbContact_SelectedIndexChanged method that the index was manually changed thanks to the code. A class member would do the job, something like:
private bool fromCode;
private void lbContact_SelectedIndexChanged(object sender, EventArgs e)
{
if (fromCode)
return;
// Do the job
}
private void tbLast_TextChanged(object sender, EventArgs e)
{
fromCode = true;
lbContact.SetSelected(lbContact.FindString(tbLast.Text), true);
fromCode = false;
}
[Personal remark]
I would also create a Contact struct/class to store your information along with a collection in your form so that you only have to access your file twice:
At loading, so that you can populate your collection
At closing, so that you can save the changes to your file
[Update]
My last remark can be not relevant as I do not have the context in which you are developing your application, that's why I said it was a personal point of view, you don't have to do it.
[Update 2]
What you can do to avoid access your file each time your lbContact_SelectedIndexChanged event is called:
Create a structure or a class to store your contacts information (firstname, lastname, adress, ...)
Create a collection (as a class member of your form) that will contain the contacts (like a List<Contact>)
In your frmContact_Load method, fill this collection with the data contained in the file instead of populating your listbox
So that in your lbContact_SelectedIndexChanged method you will search inside the collection instead of opening your file
Your Add() and Delete() operations must also modify the collection and not the file anymore
Remember to save your collection back to your file at application closing
Hope it helped.

I found the solution (for whoever encounters similar problem), the answer is in the textbox.focused :) and combined with listbox.setselected from Tim.
private void tbLast_TextChanged(object sender, EventArgs e)
{
if (tbLast.Focused && tbLast.Text != "")
{
if (lbContact.FindString(tbLast.Text) > -1)
{
lbContact.SetSelected(lbContact.FindString(tbLast.Text), true);
}
}
}
private void lbContact_SelectedIndexChanged(object sender, EventArgs e)
{
//show details of contact selected in listbox
string findNames = lbContact.GetItemText(lbContact.SelectedItem);
StreamReader obRead = new StreamReader(fileName);
using (obRead)
{
while (!obRead.EndOfStream)
{
string rdLine = obRead.ReadLine();
if (rdLine.StartsWith(findNames))
{
string[] tmpArr = rdLine.Split(',');
if (!tbLast.Focused)
{
tbLast.Text = tmpArr[0];
tbFirst.Text = tmpArr[1].Trim();
tbAddr.Text = tmpArr[2].Trim();
tbSub.Text = tmpArr[3].Trim();
tbPost.Text = tmpArr[4].Trim();
tbEmail.Text = tmpArr[5].Trim();
tbPhone.Text = tmpArr[6].Trim();
tbMob.Text = tmpArr[7].Trim();
}
}
}
lbContact.SelectedIndex = lbContact.FindString(findNames);
}
}

using string in other method

i have the following code. i need to do this:
public void Window1()
{
InitializeComponent();
opendirectory();
}
public void opendirectory()
{
Stream checkStream = null;
Microsoft.Win32.OpenFileDialog openFileDialog = new Microsoft.Win32.OpenFileDialog();
openFileDialog.Multiselect = false;
if ((bool)openFileDialog.ShowDialog())
{
try
{
if ((checkStream = openFileDialog.OpenFile()) != null)
{
// i need the following code to be stored as a string
string antcbatchlocation = openFileDialog.FileName;
}
}
catch (Exception ex)
{
System.Windows.MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
}
}
else
{
System.Windows.MessageBox.Show("Problem occured, try again later");
}
}
then i will use that string in a later button event:
public void BuildButton_Click(object sender, RoutedEventArgs e)
{
System.Diagnostics.Process runantc = new System.Diagnostics.Process();
runantc.StartInfo.FileName = antcbatchlocation;
}
Perhaps something is wrong with this string as a variable. Seems to be like string antcbatchlocation is declared local variable. If so how should i go about fixing it? Please help thanks!

You should declare your string as a private member of your Window1 class, rather than a local variable in your opendirectory method. Then, in your button click method, simply check to make sure your string is not null, so you know the user has gone through your dialog and selected a file first.

You need to use an instance variable. That means that it's a variable that is local to the class instance (in this case `Window1). This also means that it's accessible to any method inside that class instance.
Add this line of code in your class declreation, just above the public Window1(){} constructor.
private string _BatchLocation;
then inside the opendirectory() method, instead of creating a local string variable, set the openFileDialog.FileName to this instance variable.
_BatchLocation = openFileDialog.FileName;
you can then access this in the click event handler... thus your code will look like this:
runantc.StartInfo.FileName = _BatchLocation;
Have a look at this post for more information: http://www.codeguru.com/csharp/csharp/cs_syntax/anandctutorials/article.php/c5829

Google Suggestish text box (autocomplete)

What would be the best way to develop a text box that remembers the last x number of entries that were put into it. This is a standalone app written with C#.

This is actually fairly easy, especially in terms of showing the "AutoComplete" part of it. In terms of remembering the last x number of entries, you are just going to have to decide on a particular event (or events) that you consider as an entry being completed and write that entry off to a list... an AutoCompleteStringCollection to be precise.
The TextBox class has the 3 following properties that you will need:
AutoCompleteCustomSource
AutoCompleteMode
AutoCompleteSource
Set AutoCompleteMode to SuggestAppend and AutoCompleteSource to CustomSource.
Then at runtime, every time a new entry is made, use the Add() method of AutoCompleteStringCollection to add that entry to the list (and pop off any old ones if you want). You can actually do this operation directly on the AutoCompleteCustomSource property of the TextBox as long as you've already initialized it.
Now, every time you type in the TextBox it will suggest previous entries :)
See this article for a more complete example: http://www.c-sharpcorner.com/UploadFile/mahesh/AutoCompletion02012006113508AM/AutoCompletion.aspx
AutoComplete also has some built in features like FileSystem and URLs (though it only does stuff that was typed into IE...)

#Ethan
I forgot about the fact that you would want to save that so it wasn't a per session only thing :P But yes, you are completely correct.
This is easily done, especially since it's just basic strings, just write out the contents of AutoCompleteCustomSource from the TextBox to a text file, on separate lines.
I had a few minutes, so I wrote up a complete code example...I would've before as I always try to show code, but didn't have time. Anyway, here's the whole thing (minus the designer code).
namespace AutoComplete
{
public partial class Main : Form
{
//so you don't have to address "txtMain.AutoCompleteCustomSource" every time
AutoCompleteStringCollection acsc;
public Main()
{
InitializeComponent();
//Set to use a Custom source
txtMain.AutoCompleteSource = AutoCompleteSource.CustomSource;
//Set to show drop down *and* append current suggestion to end
txtMain.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
//Init string collection.
acsc = new AutoCompleteStringCollection();
//Set txtMain's AutoComplete Source to acsc
txtMain.AutoCompleteCustomSource = acsc;
}
private void txtMain_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
//Only keep 10 AutoComplete strings
if (acsc.Count < 10)
{
//Add to collection
acsc.Add(txtMain.Text);
}
else
{
//remove oldest
acsc.RemoveAt(0);
//Add to collection
acsc.Add(txtMain.Text);
}
}
}
private void Main_FormClosed(object sender, FormClosedEventArgs e)
{
//open stream to AutoComplete save file
StreamWriter sw = new StreamWriter("AutoComplete.acs");
//Write AutoCompleteStringCollection to stream
foreach (string s in acsc)
sw.WriteLine(s);
//Flush to file
sw.Flush();
//Clean up
sw.Close();
sw.Dispose();
}
private void Main_Load(object sender, EventArgs e)
{
//open stream to AutoComplete save file
StreamReader sr = new StreamReader("AutoComplete.acs");
//initial read
string line = sr.ReadLine();
//loop until end
while (line != null)
{
//add to AutoCompleteStringCollection
acsc.Add(line);
//read again
line = sr.ReadLine();
}
//Clean up
sr.Close();
sr.Dispose();
}
}
}
This code will work exactly as is, you just need to create the GUI with a TextBox named txtMain and hook up the KeyDown, Closed and Load events to the TextBox and Main form.
Also note that, for this example and to make it simple, I just chose to detect the Enter key being pressed as my trigger to save the string to the collection. There is probably more/different events that would be better, depending on your needs.
Also, the model used for populating the collection is not very "smart." It simply deletes the oldest string when the collection gets to the limit of 10. This is likely not ideal, but works for the example. You would probably want some sort of rating system (especially if you really want it to be Google-ish)
A final note, the suggestions will actually show up in the order they are in the collection. If for some reason you want them to show up differently, just sort the list however you like.
Hope that helps!

I store the completion list in the registry.
The code I use is below. It's reusable, in three steps:
replace the namespace and classname in this code with whatever you use.
Call the FillFormFromRegistry() on the Form's Load event, and call SaveFormToRegistry on the Closing event.
compile this into your project.
You need to decorate the assembly with two attributes: [assembly: AssemblyProduct("...")] and [assembly: AssemblyCompany("...")] . (These attributes are normally set automatically in projects created within Visual Studio, so I don't count this as a step.)
Managing state this way is totally automatic and transparent to the user.
You can use the same pattern to store any sort of state for your WPF or WinForms app. Like state of textboxes, checkboxes, dropdowns. Also you can store/restore the size of the window - really handy - the next time the user runs the app, it opens in the same place, and with the same size, as when they closed it. You can store the number of times an app has been run. Lots of possibilities.
namespace Ionic.ExampleCode
{
public partial class NameOfYourForm
{
private void SaveFormToRegistry()
{
if (AppCuKey != null)
{
// the completion list
var converted = _completions.ToList().ConvertAll(x => x.XmlEscapeIexcl());
string completionString = String.Join("¡", converted.ToArray());
AppCuKey.SetValue(_rvn_Completions, completionString);
}
}
private void FillFormFromRegistry()
{
if (!stateLoaded)
{
if (AppCuKey != null)
{
// get the MRU list of .... whatever
_completions = new System.Windows.Forms.AutoCompleteStringCollection();
string c = (string)AppCuKey.GetValue(_rvn_Completions, "");
if (!String.IsNullOrEmpty(c))
{
string[] items = c.Split('¡');
if (items != null && items.Length > 0)
{
//_completions.AddRange(items);
foreach (string item in items)
_completions.Add(item.XmlUnescapeIexcl());
}
}
// Can also store/retrieve items in the registry for
// - textbox contents
// - checkbox state
// - splitter state
// - and so on
//
stateLoaded = true;
}
}
}
private Microsoft.Win32.RegistryKey AppCuKey
{
get
{
if (_appCuKey == null)
{
_appCuKey = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(AppRegistryPath, true);
if (_appCuKey == null)
_appCuKey = Microsoft.Win32.Registry.CurrentUser.CreateSubKey(AppRegistryPath);
}
return _appCuKey;
}
set { _appCuKey = null; }
}
private string _appRegistryPath;
private string AppRegistryPath
{
get
{
if (_appRegistryPath == null)
{
// Use a registry path that depends on the assembly attributes,
// that are presumed to be elsewhere. Example:
//
// [assembly: AssemblyCompany("Dino Chiesa")]
// [assembly: AssemblyProduct("XPathVisualizer")]
var a = System.Reflection.Assembly.GetExecutingAssembly();
object[] attr = a.GetCustomAttributes(typeof(System.Reflection.AssemblyProductAttribute), true);
var p = attr[0] as System.Reflection.AssemblyProductAttribute;
attr = a.GetCustomAttributes(typeof(System.Reflection.AssemblyCompanyAttribute), true);
var c = attr[0] as System.Reflection.AssemblyCompanyAttribute;
_appRegistryPath = String.Format("Software\\{0}\\{1}",
p.Product, c.Company);
}
return _appRegistryPath;
}
}
private Microsoft.Win32.RegistryKey _appCuKey;
private string _rvn_Completions = "Completions";
private readonly int _MaxMruListSize = 14;
private System.Windows.Forms.AutoCompleteStringCollection _completions;
private bool stateLoaded;
}
public static class Extensions
{
public static string XmlEscapeIexcl(this String s)
{
while (s.Contains("¡"))
{
s = s.Replace("¡", "¡");
}
return s;
}
public static string XmlUnescapeIexcl(this String s)
{
while (s.Contains("¡"))
{
s = s.Replace("¡", "¡");
}
return s;
}
public static List<String> ToList(this System.Windows.Forms.AutoCompleteStringCollection coll)
{
var list = new List<String>();
foreach (string item in coll)
{
list.Add(item);
}
return list;
}
}
}
Some people shy away from using the Registry for storing state, but I find it's really easy and convenient. If you like, You can very easily build an installer that removes all the registry keys on uninstall.