Update Text always or IF first??

Question

0.00/5 (No votes)

See more:

This may sound like a pretty dumb question, and maybe in fact it is, but I had always this clue and where never clear to get the correct answer.

In terms of performance, when you are updating/monitoring a string, what is more important, always update the string no matter if it changed, or first put an IF statement and see if the string has changed and if so, update?

Maybe its not clear, so we will take a practical example, assume we are running a thread or a timer that is checking,every 100ms the count of process, from Process.GetProcesses

Label1.Text = Process.GetProcesses.Count

Vs.

if Process.GetProcesses.Count <> Label1.Text Then
  Label1.Text = Process.GetProcesses.Count
end if

Vs. (and I read that .Equals is faster

if Not Label1.Text.Equals(Process.GetProcesses.Count) Then
  Label1.Text = Process.GetProcesses.Count
end if

The reason I assume that always setting the text without IF should be faster is that you are not querying the process.getprocesses.count class two times, but on the other hand, it's forcing the label to update its properties...

What are the best practices to this?

Posted 10-Jan-11 23:17pm

creizlein

Updated 10-Jan-11 23:43pm

Dalek Dave

v2

Add a Solution

3 solutions

Solution 1

I'm pretty confident that

VB

if Process.GetProcesses.Count <> LastCount Then
  LastCount = Process.GetProcesses.Count
  Label1.Text = LastCount   
end if

Where LastCount is an Integer variable, member of your class, would perform better.
:)

Posted 10-Jan-11 23:44pm

CPallini

Solution 3

When it comes to drawing to screen, checking the need to do the actual drawing is almost always faster than just drawing with the risk it isn't really necessary. This is because the drawing is a very expensive operation.

However, it could be that the label component checks this by itself and could internally check the old value against the new value before actually applying it.

Another thought might be; how often do you update the label? Is it even worth thinking about right now? I cannot imagine that it would be a bottleneck in your application unless you would call the repaint directly (which shouldn't be done by the way)

Well, hopefully this gives you some ideas about it.

Good luck!

Posted 10-Jan-11 23:59pm

E.F. Nijboer

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Espen Harlinn · Accepted Answer · 2011-01-10T23:52:00

the property setter for the label probably looks something like this:

set
{
  if(text != value)
  {
    text = value;
    ...
    // some code to invalidate label causing an eventual repaint
    ...
    OnPropertyChanged("Text");
  }
}

if Process.GetProcesses.Count <> Label1.Text Then  
  Label1.Text = Process.GetProcesses.Count
end if

The Process.GetProcesses.Count <> Label1.Text causes Count to be converted to text before doing the string compare

Label1.Text = Process.GetProcesses.Count causes count to be converted to test once more.

So I guess I would just assign the value.

Regards
Espen Harlinn