Input Validation Checking for Numeric Values. The Val function will convert an empty text box into a value of zero. The Val function will also convert a string input to a zero value. The programmer should be aware that this numeric value is now capable of being used in calculations. The programmer may need to add other input validation if this will cause invalid calculations.
Data validation checks the reasonableness or appropriateness of the value in a variable or property.
Since an error will occur if the data placed in a text box are not numeric, a popular validation tool is the IsNumeric function. Checking for a Range of Values Checking for a Required Field using the Trim function. SetFocus Else 'Culculate sales tax. If Performing Multiple Validations 'Validate numeric entries. SetFocus Else 'Calculate and display charge for current item.