This guide discusses VBScript procedures.
In VBScript, there are two kinds of procedures; the
Sub procedure and the
Sub procedure is a series of VBScript statements (enclosed by
End Sub statements) that perform actions but don’t return a value. A
Sub procedure can take arguments (constants, variables, or expressions that are passed by a calling procedure). If a
Sub procedure has no arguments, its
Sub statement should include an empty set of parentheses
Sub procedure uses two intrinsic, or built-in, VBScript functions, MsgBox and InputBox, to prompt a user for information. It then displays the results of a calculation based on that information. The calculation is performed in a
Function procedure created using VBScript. The
Function procedure is shown after the following discussion.
Sub ConvertTemp() temp = InputBox("Please enter the temperature in degrees F.", 1) MsgBox "The temperature is " & Celsius(temp) & " degrees C." End Sub
Function procedure is a series of VBScript statements enclosed by the
Function and End
Function statements. A
Function procedure is similar to a
Sub procedure, but can also return a value. A
Function procedure can take arguments (constants, variables, or expressions that are passed to it by a calling procedure). If a
Function procedure has no arguments, its
Function statement should include an empty set of parentheses. A
Function returns a value by assigning a value to its name in one or more statements of the procedure. The return type of a
Function is always a Variant.
In the following example, the Celsius
Function calculates degrees Celsius from degrees Fahrenheit. When the
Function is called from the
Sub procedure, a variable containing the argument value is passed to the
Function. The result of the calculation is returned to the calling procedure and displayed in a message box.
Sub ConvertTemp() temp = InputBox("Please enter the temperature in degrees F.", 1) MsgBox "The temperature is " & Celsius(temp) & " degrees C." End Sub Function Celsius(fDegrees) Celsius = (fDegrees - 32) * 5 / 9 End Function
Getting Data In and Out
Each piece of data is passed into your procedures using an argument. Arguments serve as placeholders for the data you want to pass into your procedure. You can name your arguments any valid variable name. When you create a procedure using either the
Sub statement or the
Function statement, parentheses must be included after the name of the procedure. Any arguments are placed inside these parentheses, separated by commas. For example, in the following example,
fDegrees is a placeholder for the value being passed into the Celsius function for conversion.
Function Celsius(fDegrees) Celsius = (fDegrees - 32) * 5 / 9 End Function
To get data out of a procedure, you must use a
Function. Remember, a
Function procedure can return a value; a
Sub procedure cannot.
Sub and Function
Function in your code must always be used on the right side of a variable assignment or in an expression. For example:
Temp = Celsius(fDegrees)
MsgBox "The Celsius temperature is " & Celsius(fDegrees) & " degrees."
To call a
Sub procedure from another procedure, type the name of the procedure along with values for any required arguments, each separated by a comma. The
Call statement is not required, but if you do use it, you must enclose any arguments in parentheses.
The following example shows two calls to the
MyProc procedure. One uses the
Call statement in the code; the other does not. Both do exactly the same thing.
Call MyProc(firstarg, secondarg) MyProc firstarg, secondarg
Notice that the parentheses are omitted in the call when the
Call statement is not used.