my question is about c#

Question

0.00/5 (No votes)

See more:

int rows = Convert.ToInt32(txtrows.Text.ToString());
txtrows is the id of a text box..
when the textbox is empty,the an error accour (your input string is not in correct format ) .. if the text is not empty then is does not show any error..
any solution ??

Posted 23-Sep-14 5:25am

mudi lala

Add a Solution

Comments

Simon_Whale 23-Sep-14 11:37am

There is also no need to do txtrows.Text.ToString() as the Text property is always a string

some further reading for you http://msdn.microsoft.com/en-us/library/a19tt6sk(v=vs.110).aspx

6 solutions

Solution 6

Why not use the full power of the 'TryParse operator:

C#

// this code requires:
using System.Globalization;
//
// note: prior to .NET 4 an invalid culture specification string would
// throw an 'ArgumentException. in .NET 4 the exception thrown is
// a 'CultureNotFoundException
CultureInfo cultureProvider = new CultureInfo("en-US");

int rows;

if (Int32.TryParse(txtrows.Text, NumberStyles.Integer, cultureProvider , out rows))
{
    // valid integer now in 'rows
}
else
{
    // handle no content, or invalid content, in the TextBox
    throw new ArgumentException("Invalid entry in 'txtrow");
}

Posted 23-Sep-14 6:11am

BillWoodruff

Comments

Philippe Mori 23-Sep-14 20:31pm

Not so much usefull in practiceto use TryParse if you throw an exception anyway. You can simply call Parse in that case.

BillWoodruff 24-Sep-14 2:34am

Thanks, Philippe, my intent was to indicate one possible thing ... throw an exception ... if the result of 'TryParse was 'false. I did not mean to imply that throwing was the only thing one could do :)

cheers, Bill

Raul Iloc 24-Sep-14 1:09am

You have my 5+ vote, because you solution is managing also for multilanguage context where problems may occur for numbers and date time user input conversion.

BillWoodruff 24-Sep-14 2:34am

Thanks, Raul !

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)

Sergey Alexandrovich Kryukov · Accepted Answer · 2014-09-23T05:31:00

How else? Did you expect that, if your string is empty, 42 would be returned? Or some other number?

Instead of Convert use either int.Parse (may throw exception as well), or int.TryParse (will return Boolean to indicate success). At least the names of these methods are adequate and tell us what really happens. Please see:
http://msdn.microsoft.com/en-us/library/system.int32.parse%28v=vs.110%29.aspx[^],
http://msdn.microsoft.com/en-us/library/system.int32.tryparse%28v=vs.110%29.aspx[^].

Please learn what all 6 methods do. :-)

—SA

Raul Iloc · Accepted Answer · 2014-09-23T05:30:00

Solution 2

You should use TryParse [^] and this method will convert the string to 0 for possible exceptions, and in your case for empty string.

Posted 23-Sep-14 5:30am

Raul Iloc

Ravi Bhavnani · Accepted Answer · 2014-09-23T05:27:00

Solution 1

This will use the default value (zero) of Int32 if the parse fails (for whatever reason):

int rows = 0;
Int32.TryParse (txtRows.Text, out rows);

/ravi

Posted 23-Sep-14 5:27am

Ravi Bhavnani

Comments

Philippe Mori 23-Sep-14 20:28pm

Not necessary to initialize rows to 0 as it is an output parameter and output parameters need to be initialized Inside the function.

Ravi Bhavnani 24-Sep-14 7:59am

It's just my coding style to perform explicit initialization, but you're right - it's unnecessary.

/ravi

ChauhanAjay · Accepted Answer · 2014-09-23T05:30:00

Solution 3

Check the below links
http://stackoverflow.com/questions/8321514/input-string-was-not-in-a-correct-format[^]

http://stackoverflow.com/questions/21937254/input-string-was-not-in-a-correct-format-error[^]

Hope they help.

Posted 23-Sep-14 5:30am

ChauhanAjay

PeejayAdams · Accepted Answer · 2014-09-23T05:31:00

Solution 5

Testing for null or empty is a good start e.g.

C#

if (!string.IsNullOrEmpty(txtRows.Text.ToString())
    rows = Convert.ToInt32(txtrows.Text.ToString())
else
    rows = 0;

You may also want to look at the int.TryParse() method.

Posted 23-Sep-14 5:31am

PeejayAdams

v2

my question is about c#

6 solutions

Solution 6

Solution 4

Solution 2

Solution 1

Solution 3

Solution 5

Add your solution here

Preview 0

Existing Members

...or Join us