Excel VBA Sub Routine Vs Function

What is the difference between Subroutine and Function:

The Sub(routine) can NOT return a value. But a Function can return a value. If you want to call them then a Function can be called by it’s name with variables in parenthesis and  a Subroutine can be called only by writing it name with variables without parenthesis as explained below.

Subroutine (Sub) Syntax with Example:                                                              

Sub  Add(x as integer, y as integer, z as integer)

z= x+y

End Sub

Calling Subroutine

Add  x, y, z
when it will return result will be saved in z variable, so it has not returned anything.

Function Syntax with Example:                                                                 

Function  Add(x as integer, y as integer) as integer

add= x+y        

End Function

Calling Function

T=Add( x, y)

when it will return result will be stored in ‘T’ variable. The function always returns a value so its value must be saved in some variable

More Explanation:

Sub

The easiest way to think of a sub vs a function is that a function can return a value and a sub cannot.  A sub can be thought of as a small program that performs some action that is contained within the program.  Subs can be used to update a cell or perform an import and calculation, but the result can’t be returned to another sub or function. Another thing to note is that a sub (or macro) cannot be accessed directly by a cell reference.  For example, when a cell is used to show today’s date, =Today(), that formula is also a built-in function, not a sub.

Function

A function is similar similar to a sub, except that a function can return a value.  It may be easier to think of a function as similar to a formula in excel.  You can provide the function the necessary inputs and the function returns the desired value.  You can build a custom function for just about any action and then access that function from either a call from a macro, or a direct reference from a cell.