functions VS procedure

I have an assignment for my VB.NET class to compare functions and procedures and it has me completely confused. I wrote a program that does a bunch of math, etc. and I am required to change the following to a procedure, but all it does is mess up the whole program. Can someone please help me out a little here? Thanks,

Andrew

Private Function GetFwtTax(ByVal sngWeekPay As Single) As _ Single

-When I change Function to "Sub", the "As Single" shows erros.



What all do I need to change in the code? I am thoroughly confused about the difference between a function and procedure. HELP!!!!!!!! Thanks!

A function returns a value (or CAN) where as a sub (procedure) doesn't (at least not directly). In a function the As blah blah blah is declaring the return type or the type of the value that it will return. Since a sub can't return a value like that it gives you an error. A sub can however change the value of an argument and expose those changes to the rest of the program if the argument is passed in ByRef.

VB Code:

'function way
Private Function GetFwtTax(ByVal sngWeekPay As Single) As Single
   Return 1.1
End Function
 
dim ret as Single=GetFwtTax(1) 'returns 1.1
 
'sub way
Private Sub GetFwtTax(ByVal sngWeekPay As Single,[b]ByRef[/b] sngReturn as Single)
   sngReturn=1.1
End Sub
 
dim ret as Single
GetFwtTax(1,ret) 'ret now equals 1.1