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:
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