In VBScript, there are two kinds of procedures; the Sub procedure and the Function procedure.
11.1 Sub Procedures
A Sub procedure is a series of VBScript statements (enclosed by Sub and 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 must include an empty set of parentheses ().
Syntax:
Sub Procedure name ()
Statements
-----------
-----------
End Sub
Or
Sub Procedure name (argument1, argument2)
Statements
-----------
-----------
End Sub
Example: 1
Sub ConvertTemp()
temp = InputBox("Please enter the temperature in degrees F.", 1)
MsgBox "The temperature is " & Celsius(temp) & " degrees C."
End Sub
Example: 2
11.2 Function Procedures
A 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 must 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.
Syntax:
Function Procedure name ()
Statements
-----------
-----------
End Function
Or
Function Procedure name (argument1, argument2)
Statements
-----------
-----------
End Function
Example: 1
Function Celsius(fDegrees)
Celsius = (fDegrees - 32) * 5 / 9
End Function
Example: 2
Function cal(a,b,c)
cal = (a+b+c)
End Function
11.3 Getting Data into and out of Procedures
o Each piece of data is passed into our procedures using an argument.
o Arguments serve as placeholders for the data we want to pass into our procedure. We can name our arguments any valid variable name.
o When we create a procedure using either the Sub statement or the Function statement, parentheses must be included after the name of the procedure.
o Any arguments are placed inside these parentheses, separated by commas.
11.4 Using Sub and Function Procedures in Code
A Function in our code must always be used on the right side of a variable assignment or in an expression.
For example:
Temp = Celsius(fDegrees) -Or-
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 doesn't. 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 isn't used.
