Validate a TextBox Using an Error Provider in C#

Validating a textbox Using an Error Provider in C#
is very important and there are many ways on how to do it. But, in this tutorial, I’m going to teach you the simplest way on how to validate a textbox by using an error provider. Error provider displays a user-friendly message to notify the user whenever validation fails. Then, that’s the time for the user to correct the error and validate the message in the textbox.

Let’s begin:

Open Microsoft Visual Studio and create a new windows form application. Then, drag two text boxes, labels, button and an error provider.

After setting up the form, double-click the “check” button and do the following codes for validating the textboxes.

 private void button1_Click(object sender, EventArgs e)
 {
 //'CHECKING IF THE TWO TEXTBOXES ARE CLEARED.
 if(txtStr .Text == "" )
 {
 //'THE ERROR PROVIDER WILL APPEAR AND IT WILL INFORM THE PROBLEM TO THE USER.
 errorProvider1.SetError(txtStr, "Textbox must be filled up.");
 
 }else if(txtInt .Text == ""){
 //'THE ERROR PROVIDER WILL APPEAR AND IT WILL INFORM THE PROBLEM TO THE USER.
 errorProvider1.SetError(txtInt, "Textbox must be filled up.");
 }
 else
 {
 //'SET THE ERROR PROVIDER TO BE CLEARED.
 errorProvider1.SetError(txtStr, "");
 errorProvider1.SetError(txtInt, "");
 //'CHECKING IF YOU HAVE INPUT A NUMERIC VALUE.
 if (!System.Text.RegularExpressions.Regex.IsMatch(txtStr.Text, "[^0-9]"))
 {
 //'THE ERROR PROVIDER WILL APPEAR AND IT WILL INFORM THE PROBLEM TO THE USER.
 errorProvider1.SetError(txtStr, "You have input a numeric value that is not valid.");

 }
 if (System.Text.RegularExpressions.Regex.IsMatch(txtInt.Text, "[^0-9]"))
 {
 //'THE ERROR PROVIDER WILL APPEAR AND IT WILL INFORM THE PROBLEM TO THE USER.
 errorProvider1.SetError(txtInt, "You have input a string value that is not valid.");

 }
 

 }

Output:

For all students who need a programmer for your thesis system or anyone who needs a source code in any programming languages. You can contact me @ :

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You can try the Visual Basic.Net version of Validation textbox error using the ErrorProvider Tool.

Download Sourcecode