Page 96 - TCS ICT Book 8

The City School 2021-2022

1. Now go back to the form and

double click on the button to open
the script window

2. It is highly recommended to use
the comments while using code

from a module to remember its
functionality. Commenting is easy

in VB using a ‘ single quote.
3. To use the Subroutine/Function in

this form we will simply write its
name in this case Pakistan().

4. The green line above the sub with
a single ‘ quote is the comment.

4.14. 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. To
demonstrate error handling, we will deal with

the error of entering non-numeric data into text Checkpoint
boxes that are supposed to hold numeric values.

The program_label here is error_hanldler. When Function is a type of procedure that
returns a value that is passed on to
the user enters non-numeric values into the the main procedure to finish
execution.
textbox, the error message will display the text A module is used to organise code
and wrap up variables, properties,
“One of the entries is not a number! Try again!” If events, and procedures of similar

no error occurs, it will display the correct answer. use.

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