Error message not working for textbox value

Question

1.00/5 (1 vote)

See more:

I have a web form that has three textboxes on it. The first two do calculation and the answer goes into textbox3. I am trying to display a message that will only display if the value in textbox3 is 50 or greater. Here is my code:

C#

if (TextBoxHC50.Text < 50)
        {
            lblMessage.Text = "Your answer has increased more than 50%,";
        }
        else if (TextBoxHC50.Text > 50)
        {
            
        }

What am I doing wrong for this not to work?

Posted 13-Oct-14 6:31am

Computer Wiz99

Add a Solution

2 solutions

Solution 2

You cannot compare a string with integer value, like your 50. (You should not also hard-code immediate constants; this is bad for maintenance; better declare explicit constants, do it just once.)

Also, you are not taking into account that the text box input can be not a valid string representing an integer value. Assuming you want to work with the int type, use int.TryParse. You could use int.Parse, too, but then get ready to handle possible exceptions.

—SA

Posted 13-Oct-14 6:48am

Sergey Alexandrovich Kryukov

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)

SteveyJDay · Accepted Answer · 2014-10-13T06:44:00

Solution 1

Try converting your value first.

C#

int iTextBoxValue = Convert.ToInt32(TextBoxHC50.Text);
if (iTextBoxValue < 50) {
    lblMessage.Text = "Your answer has increased more than 50%,";

} else if (iTextBoxValue > 50) {
}

Posted 13-Oct-14 6:44am

SteveyJDay

Comments

Sergey Alexandrovich Kryukov 13-Oct-14 12:49pm

Convert should not be used. This is really the parsing. How do you take into account that the input is not valid, not parsable as Int32?
Please see my answer.
—SA

SteveyJDay 13-Oct-14 14:51pm

My assumption was the input had been validated by this point in code.

Sergey Alexandrovich Kryukov 13-Oct-14 15:37pm

No, it cannot be. If parsing is not yet done, it cannot be considered validated. If if is done, converting would be pointless, because the side effect of validation is always having some recognized integer value. If you think that validation can be done in some other way, think again. For example, even if the input is only digits (which can be achieved by filtering and would be very reasonable), it still can be invalid (if value is more than int.MaxValue). If you think that validation should be done separately from getting the value, also think again. Repeating potentially similar action is a sign of poor design. So, from all points of view, your advice is wrong.
—SA

Computer Wiz99 13-Oct-14 16:13pm

That works for me. Question, what is the best way to round value?

Sergey Alexandrovich Kryukov 13-Oct-14 16:36pm

Math.Round.
However, most likely, you don't need any rounding (which can be dangerous, because you can get loss of precision). Most likely, you need just proper string formatting, to show rounded value on screen. This is not the same. If you explain your problem (separate question, perhaps), I'll answer.
Do yourself a big favor: don't follow the advice in this answer.
—SA

SteveyJDay 13-Oct-14 16:37pm

Then post a "working" solution with code...

Sergey Alexandrovich Kryukov 13-Oct-14 16:48pm

Why? I already posted an answer. Everything is clear.
Look, you should feel some responsibility for answers you post. I explained why your answer is unacceptable. Have some shame.
—SA

SteveyJDay 13-Oct-14 17:05pm

You posted an explanation of why it was not working. A solution involves code that shows how it should work. Notice the heading say solutions and not answers.

Under your suggestion if I have multiple controls that cause a post back I would have to rewrite the validation logic in each post back. I quote "Repeating potentially similar action is a sign of poor design."

Sergey Alexandrovich Kryukov 13-Oct-14 17:09pm

Okay, OP is warned, and you are not getting it. Everyone can read it and make appropriate conclusion. You told about yourself by yourself. Fair enough. End of story.
Thank you.
—SA