Functions, procedures and sub procedures - when to choose what?

Ok, so I decided to learn VBA and have been looking through an online tutorial today. In this tutorial it didn't give a clear reason for when to select which of these ("a sub procedure is like a function except it cannot return values" - ok, so why use it, then?).

While trying to understand this well enough to be able to ask a not completely retarded question I think I've picked up that both function and sub are procedures. Ok, so at least now we're down to two. But WHY would one choose a sub over a function if a function can do everything a sub can do, only better?

Cheers!

Cos programmers mainly use functions within subroutines.

eg, you have a function that polls a webpage and returns a value, it's 25 lines of code long. You're going to use this section of code a lot in various different subroutines in your project so you've created a function that you can call from any sub at any time with 1 line of code rather than 25.

Originally Posted by BellyGas

Cos programmers mainly use functions within subroutines.

eg, you have a function that polls a webpage and returns a value, it's 25 lines of code long. You're going to use this section of code a lot in various different subroutines in your project so you've created a function that you can call from any sub at any time with 1 line of code rather than 25.

Ok? But a sub would only be good if you don't want something returned, right? Say I want to grab something from a table, do magic on it and insert it into another table - that would work for a sub? Is it so that only in the cases where I need something like =doSomething(c1) in a cell a sub is preferred? But is there a reason not to use a function in place of a sub?

@quekbc

a sub procedure allows you more interaction with Excel - e.g. you can format cells in a Sub, not in a Function. A Sub can do copy and pastes, and function cannot.

That's not strictly true (well it's a bit misleading anyway), one can do all those things in a Function, just not when called from a worksheet function.

Put simply if you want to return something, use a function, if you don't then use a Sub

Originally Posted by Kyle123

That's not strictly true (well it's a bit misleading anyway), one can do all those things in a Function, just not when called from a worksheet function.

Thanks. I noticed that after I posted the reply, hence an added disclaimer - didn't want to over-complicate matters but I guess I inadvertently did.

I reckon so, changing stuff on a worksheet is just as simple in a function as a sub

Just to complicate it further, you can return values from a sub as well. Whoever told the OP you can't is just plain wrong.

@BellyGas

Discounting ByRef (since it's not really returning), how does one return a value from a sub?