C# code to validate given string in textbox is number or character

This code will useful for validating zip Code, telephone no where we have to enter only numbers in textbox. We can write javascript to check it or we also can use regular expression to do so. This is just another method to check it.

Code Snippet:

//Block 1:

 

string strValidationFailureMessage =””;

if (!IsNumeric(txtZipCode.Text.Trim()))

{

   strValidationFailureMessage = "Invalid Zip/Postal Code";

}

 

//Block 2:

 

private bool IsNumeric(string strData)

    {

        int i = 0;

        bool blnIsNumber = true;

        strData = strData.Trim();

 

        //validation for Numeric Value

        for (i = 0; i < strData.Length; i++)

        {

            blnIsNumber = char.IsDigit(strData[i]);

 

            if (blnIsNumber == false)

            {

                break;

            }

        }

 

        return blnIsNumber;

    }   

 

Note: txtZipcode is the id of my textbox.

 

You can use Block1 in the beginning of your submit button and if string ‘strValidationFailureMessage’ is not empty then don’t proceed with saving or whatever you want to do inside buttonclick event. Display the message to user.