SBasic language reference::Function statement

Function statement
Declares the name, arguments, and code that define a Function procedure.

Format:

  Function name [(arglist)] [ As type ]
     [ statements ]
     [ Exit Function ]
     [ statements ]
  End Function

Syntax:

name
Required. Name of the Function procedure. Must be a valid identifier.
arglist
Optional. List of variables or expressions representing arguments that are passed to the Function procedure when it is called. Multiple arguments are separated by commas. If you supply an argument list, you must enclose it in parentheses.
type
Optional. Data type of the result. Can be Integer, Floating or String; or the name of structure.
statements
Optional. A block of statements to be executed within the Function procedure.
End Function
Terminates the definition of this Function procedure.

Remarks:

1. To return a value from a function, you can either assign the value to the function name or include it in a Return statement. The following example assigns the return value to the function name MyFunction and then uses the Exit Function statement to return:

      Function MyFunction(A,B,C) As Double
         ' ...
         MyFunction = 1.23
         Exit Function
         ' ...
      End Function

If you use Exit Function without assigning a value to name, the function returns the default value appropriate to type. The Return statement simultaneously assigns the return value and exits the function, as in the following example:

      Function MyFunction(A,B,C) As Double
        ' ...
        Return 1.23
        ' ...
      End Function

Any number of Return statements can appear anywhere in the procedure. You can also mix Exit Function and Return statements.

2. You can't define a Function procedure inside another procedure.

3. The Exit Function statement causes an immediate exit from a Function procedure. Any number of Exit Function statements can appear anywhere in the procedure.

4. It's possible to call other functions and subs in function procedure but they have to be declared before current function.

5. SBasic supports recursion calls, it means you can call current Function inside it's body.

Example:

  Function Sum(A as Floating, B as Floating, C as Floating) As Floating
     Sum = A+B+C
  End Function ' Returns latest value of CalcSum.

  Function Mul(A,B,C) As Floating
     Return A*B*C
  End Function 

  ' -----------------------------------

  Input "x=",x
  Input "y=",y
  Input "z=",z

  res = Mul(x,y,z) / Sum(x,y,z)
  print "Result=", res