Page 58 - Computing Book 8

Developing Applications – Visual Studio Class 8

Program Debugging and Error Handling:

Error handling is an essential procedure in Visual Basic 2010 programming that helps make a
program error-free. The user does not have to face all sorts of problems such as program crashes or
system hangs. Errors often occur due to incorrect input from the user. For example, the user might
make the mistake of attempting to enter text (string) to a box that is designed to handle only
numeric values such as the weight of a person, the computer will not be able to perform the
arithmetic calculation for text, therefore, will create an error. These errors are known as
synchronous errors.

In this example, we will deal with the error of entering non-numeric data into text boxes that are
supposed to hold numeric values. The program_label here is error_hanldler. When the user enters
non-numeric values into the textbox, the error message will display the text “One of the entries is
not a number! Try again!” If no error occurs, it will display the correct answer.

Follow the steps below to create a program which can handle user input errors:
• Create a new form with five labels, two text boxes, and a button.
st
• Change the text of the 1 label to First Number
nd
• Change the text of the 2 label to Second Number
rd
• Change the text of the 3 label to “Division of First
Number with Second Number” and also change its size
by Maximum Size properties under Layout heading
height=20 and width = 120
th
• Change the text of the 4 label to Result and change its
name to Lbl_Answer
th
• Clear the text of the 5 label to hide it while the program
is running and name it Lbl_ErrorMsg

• Change the text of the Button to Calculate and also
change its name to CmdCalculate
st
• Change the name of the 1 text box to FirstNumber
nd
• Change the name of the 2 text box to SecondNumber
• Double click on the button to open script window and
type this code

Hiding the Error
Message box
Declaration of error
Simple Program for handing that if error
division of two occurs go to error
numbers handler

Response of error
handler in case of error.
Result Label will
displays “Error” and
ErrorMsg box which
was hidden in the first
line of code will be
visible with the Error
Message in “ ”

The City School /Academics/Computing Curriculum/Class 8/2020-2021 Page 57 of 75