Skip to main content

Dynamically removing dynamically added controls

I dynamically add controls to my form, and also i need the option to remove them again.So first i did this to remove,(as per my logic)

foreach(Control contrl in this.Controls)
{
if (contrl .GetType() == typeof(TextBox))
{
this.Controls.Remove(contrl );
}
}

But this code removed only alternative textboxes. At first i was unable to find it out,but then after searching on net i found that when you remove a control from the ControlCollection, subsequent controls are moved up to fill that space. And found the solution to my problem. The code that must be used is like below.

foreach (Control contrl in this.Controls)
{
if (contrl.GetType() == typeof(TextBox))
{
ContrlToRemove.Add((TextBox)contrl);
}
}

foreach (TextBox txtbox in ContrlToRemove)
this.Controls.Remove(txtBox);

Other Alternatives:
1. You can do it in a single loop when removing items from any sort of indexed container,it is always best to remove them in reverse order starting at the end.And also when manually removing windows controls from a container,it is best to Dispose them at the same time. Otherwise you may have a memory leak.

If you find other alternatives too keep me informed.

Comments

Popular posts from this blog

How to Install Hadoop (2.7.3) on Ubuntu (16.04 LTS)

As I am planning to learn Hadoop, I wanted to install Hadoop (2.7.3) on my Ubuntu (16.04 LTS) and I followed the steps mentioned in the documentation on the Apache Hadoop website. I encountered few problems which are mentioned below, spent some time finding solution to them.

Below are the steps I followed and the description of the error is at the end of this post and also I have mentioned what I missed and what caused these errors.


Step 1. Download Hadoop installation file. For Hadoop 2.7.3 version I used the following link 

http://www.apache.org/dyn/closer.cgi/hadoop/common/hadoop-2.7.3/hadoop-2.7.3-src.tar.gzStep 2. (Assuming you have downloaded the file into /home/<username>/Downloads folder

$ tar zxf hadoop-2.7.3-src.tar.gz
This will extract the files into a folder  "hadoop-2.7.3" .

Step 3. I moved the file to /home/<username> folder (many suggest to move it into /usr/local but I prefer to keep it here, may be once I learn more about linux I might get into tha…

Installing Adobe Reader on Ubuntu 16.04 LTS

Adobe stopped Adobe Reader support for Linux so it is bit of a challenge to find and install the Adobe Reader for Linux. Here I describe how to install it on Ubuntu 16.04 LTS.

Step 1. First install gdebi

sudo apt-get install gdebi
Step 2. Install required libraries

sudo apt-get install libgtk2.0-0:i386
sudo apt-get install libnss3-1d:i386
sudo apt-get install libnspr4-0d:i386
sudo apt-get install libxml2:i386
sudo apt-get install libxslt1.1:i386

Step 3. Download the Adobe Reader DEB package

Adobe Reader 9.5.5 enu

Javascript KeyCode Reference table for Event Handling

The post explains Keyboard event handling using javascript.Javascript events are used to capture user keystrokes. Below is a table of key codes for the keys on a multimedia keyboard. If this table is inconsistent with your own findings, please let me know.

Java Script Code to Find Key code

<script language="JavaScript">
document.onkeydown = checkKeycode
function checkKeycode(e) {
var keycode;
if (window.event) keycode = window.event.keyCode;
else if (e) keycode = e.which;
alert("keycode: " + keycode);
}
</script>


Key Code Reference Table
Key PressedJavascript Key Codebackspace8tab9enter13shift16ctrl17alt18pause/break19caps lock20escape27page up33page down34end35home36left arrow37up arrow38right arrow39down arrow40insert45delete46048149250351452553654755856957a65b66c67d68