Do not allow twice values into a textbox

Question

Hi! I have one combobox with a textbox. Inside of my combobox I have three items (Morning afternoon goodnight). Then each selection is displayed into the textBox. What I need to do? When I select morning for example I would like that even I selected the second way its not should appear twice into the textbox (only once). Its allow to appear again ONLY when the textbox its clean it. My code: private void cbxChoice_SelectedIndexChanged(object sender EventArgs e) { switch (cbxChoice.SelectedIndex) { case 0: //Morning textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.clear(); break; case 1: //Afternoon textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.clear(); break; case 2: //Night textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.clear(); break;

Azeem Anzari · Answer

Remove all boolean values declaration like isMorning isnight isafternoon and then declare only one variable at the class level as below List txtList; And then change your indexchanged event as below run the program. private void cbxChoice_SelectedIndexChanged(object sender EventArgs e) { if (textDisplay.TextLength > 0) { txtList = textDisplay.Text.Split('').ToList(); } switch (cbxChoice.SelectedIndex) { case 0: //Morning if (txtList !=null) { if (!txtList.Contains(Morning)) { textDisplay.Text += cbxChoice.Text +  + Environment.NewLine; break; } } else { textDisplay.Text += cbxChoice.Text + ; textDisplay.Text += Environment.NewLine; break; } break; case 1: //Afternoon if (txtList != null) { if (!txtList.Contains(
After Noon)) { textDisplay.Text += cbxChoice.Text +  ; textDisplay.Text += Environment.NewLine; break; } } else { textDisplay.Text += cbxChoice.Text + ; textDisplay.Text += Environment.NewLine; break; } break; case 2: //Night if (txtList != null) { if (!txtList.Contains(
Night)) { textDisplay.Text += cbxChoice.Text + ; textDisplay.Text += Environment.NewLine; break; } } else { textDisplay.Text += cbxChoice.Text + ; textDisplay.Text += Environment.NewLine; break; } break; } } Accept as answer if working regards

Israel · Answer

It's a great job. Thanks to be patient with me. Thanks again!

Israel · Answer

Dear Azeem your codes it's working very very well. But there is a little point that you forgot. Or in other way right now its do well the job. But when I clean my textbox if I reselect the same item its will not display it into textbox (only when I restart my program). Excuse me to insist on this point.

Azeem Anzari · Answer

Change your selected index changed event to the below code I tested everything works as expected also attached the source for your reference. private void cbxChoice_SelectedIndexChanged(object sender EventArgs e) { switch (cbxChoice.SelectedIndex) { case 0: //Morning if (isMorning == false) { textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; isMorning = true; break; } break; case 1: //Afternoon if (isAfterNoon == false) { isAfterNoon = true; textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; break; } break; case 2: //Night if (isNight == false) { isNight = true; textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; break; } break; } }

Israel · Answer

@Azeem Please Azeem can you take 3 minutes to test it by yourself. I dont know what happen. Its doesnt work properly. These is the whole code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { Boolean isMorning = 0; Boolean isAfterNoon = 0; Boolean isNight = 0; public Form1() { InitializeComponent(); } private void cbxChoice_SelectedIndexChanged(object sender EventArgs e) { switch (cbxChoice.SelectedIndex) { case 0: //Morning if(isMorning == 0) { textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; isMorning=1; textDisplay.Clear(); break; } case 1: //Afternoon if(isAfterNoon == 0) { isAfterNoon=1; textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.Clear(); break; } case 2: //Night if(isNight==0) { isNight=1; textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.Clear(); break; }

Azeem Anzari · Answer

make it capital B and make sure you declare the variable on the class level

Israel · Answer

sound get it good. But when I run the program its give this error message: The type or namespace name 'boolean' could not be found (are you missing a using directive or an assembly reference?)

Azeem Anzari · Answer

boolean isMorning=0; boolean isAfterNoon=0; boolean isNight= 0; private void cbxChoice_SelectedIndexChanged(object sender EventArgs e) { switch (cbxChoice.SelectedIndex) { case 0: //Morning if(IsMorning == 0) { textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; isMorning=1; textDisplay.clear(); break; } case 1: //Afternoon if(isAfterNoon == 0) { IsAfterNoon=1; textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.clear(); break; } case 2: //Night if(isNight==0) { isNight=1; textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; textDisplay.clear(); break; }

Israel · Answer

good explaining. But can you do it in my codes please. That why I put my code overhere. Thanks

Azeem Anzari · Answer

there are many ways you can do that make an array with values in a textbox values should be inserted to the array if comma is found then search the array before you insert if its there dont do otherwise insert or else make a boolean variable called ismorning isafternoon isnight and update it with one if you inserted to the textbox bydefault it will be 0. check the boolean value before you insert if its 1 then dont do otherwise insert

Israel · Answer

Big excuse I couldnot put the textDisplay(). My real code are as follow: I wouldnot want to see value repeated into the textbox even I select the item again (for example morning afternoon  afternoon good night ). Its can appear ONLY when my textbox its clear. private void cbxChoice_SelectedIndexChanged(object sender EventArgs e) { switch (cbxChoice.SelectedIndex) { case 0: //Morning textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; break; case 1: //Afternoon extDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; break; case 2: //Night textDisplay.Text += 
 + Environment.NewLine + cbxChoice.Text + Environment.NewLine + ; break;

Azeem Anzari · Answer

move textDisplay.clear() above textDisplay.Text. regards