Error when trying to convert TextBox.Text value to Int32

All this string manipulation is great and fun but if the point is that the user shouldn't be entering spaces in the input, why are you letting him?

With all respect to the other folks answering this question, the solution is to keep the user on the straight and narrow rather than allowing them to type in bogus characters.

Other than as an academic exercise, I'd skip all this sting handling and int parsing and instead leverage the built-in code that has already been written.

Just derive a new control from the NumericUpDown control and have it do the heavy lifting for you.

Something like:

public partial class PercentageNumericUpDown : NumericUpDown { public PercentageNumericUpDown() { InitializeComponent(); } protected override void UpdateEditText() { this.Text = this.Value + "%"; } } 

The override of UpdateEditText() will make sure the % sign is appended for you automatically after the edit takes place.

You can set the range of valid values and just allow the user to type (or up/down the value) and you get automatic validation here too. It has Min and Max properties you can set.

It'll also allow you to set a negative range if you need that. And decimal places if you need those.

Might as well take advantage of the built-in controls when you can rather than reinventing the wheel.

Just a thought.

Try:

string valor = txtDefinavalor.Text.Trim().Replace("%", ""); if (Convert.ToInt32(valor) > 100) { txtDefinavalor.Text = "100%"; } 

If you are using winforms use a maskedtextbox that will only allow you to enter numbers, or even a numericupdown field which you can set the limits on how high and low it can go and only numbers are allowed in there.

If you are using asp.net then you should just use a validation control that won't allow them to enter certain values. Such as a range validator.

Then what I assume is a button click the comparison becomes much easier as you don't have to remove any % signs or anything of that sort. Also, when you're trying to figure out if something is a number you should use tryparse to make sure it's actually a number.

int test; if(Int32.TryParse(txtDefinavalor.Text, out test) { // do something here } else { // error condition handled here } 

Try int32.TryParse

if (rbtPercentualmensal.Checked || rbtPercentualmedioanual.Checked) { int j ; string valor = txtDefinavalor.Text.Replace("%", string.Empty); if(Int32.TryParse(valor,out j) && j > 100) { //// Do what ever you want here ... } } 

@Habib is probably right - some non-numeric character in the input string. However, my preferred method would be to remove the need to have the percent sign in the text box. Either have it in the label identifying the text box or as a label after the text box.

solved problem. i used Convert.int16, but main problem that is valor was getting wrong textbox value, so it was empty value, i think because of that i got error. Anyway that for answers. Now its working

Check this piece of example source code:

using System; namespace ConsoleApplication1 { class Program { public static string FilterText(string input) { // Replace % by spaces, then remove all spaces/tabs with Trim function. string filteredText = input.Replace("%", " ").Trim(); // Parse the text. int number = Int32.Parse(filteredText); // Fix not expected values. number = (number < 0) ? 0 : number; number = (number > 100) ? 100 : number; return number + "%"; } public static void Main(string[] args) { Console.WriteLine("\"100%\": \"" + FilterText("100%") + "\""); Console.WriteLine("\" 50%\t\t\": \"" + FilterText(" 50%\t\t") + "\""); Console.WriteLine("\"0%\": \"" + FilterText("0%") + "\""); Console.WriteLine("\"150%\": \"" + FilterText("150%") + "\""); Console.WriteLine("\" -06% \t \": \"" + FilterText(" -06% \t ") + "\""); } } } 

The output for this example is:

"100%": "100%" " 50% ": "50%" "0%": "0%" "150%": "100%" " -06% ": "0%"