Answers to Invalid, Valid Variable Name Exercise

Based on the rules for naming variables in Visual Basic indicate whether the following variable names are VALID or INVALID. Check the appropriate column for each variable name. Are the GOOD variables names?

Variable Name	Valid?	Invalid?	Good Variables Name? If not why?
GPA	YES		Yes. Assuming the application has something to do with grades this abbreviation is an acceptable variable name.
Count#1		YES	Invalid character #
$grosspay		YES	Invalid character $
GradePointAverage	YES		Yes - Descriptive
Attempted.Hours		YES	Invalid character . The period has special meaning in Visual Basic and may not be used in programmer supplied names.
Attempted-Hours		YES	Invalid character -
Interest Rate		YES	You may not use a space in a variable name
A2	YES		Not good name – Not descriptive
2A		YES	Must begin with a letter
End		YES	End is a reserved word. Reserved words have a special meaning to the compiler and may not be used for programmer supplied names
Printitout	YES		Not the greatest name. It is not clear what it means.
MONEYAFTERALLTAXES	YES		Not the greatest. All uppercase is valid but not helpful in reading the variable name. Also, while it’s length does not violate the rules it is probably too long to have to work with in code.

Rules for naming variables in Visual Basic

· Unique within scope

· <= 255 characters (other languages may have different length restrictions)

· Begin with a letter

· No embedded spaces or many special characters (. , “ - $ # * and others). The underscore _ is a valid character.

· Cannot be a reserved word

· Use upper and lower case with purpose. Once a variable is declared you do not have to be concerned with upper/lower case. The editor recognizes words that are the same except for case and makes them all the same for you. (use of upper and lower case differ between languages)

· It is always good programming practice to use names that are descriptive or mnemonic.