Re: Function Declaration

Dennis,
| If I pass a structure byval that contains both reference and value types,
| what exactly am I passing
A structure is a value type, you are receiving a copy of all the values. If
the structure contains a String field, you get a copy of the reference to a
single copy of the String object on the heap.

| if I change a structure field in my function,
| is the structure field in the calling procedure changed also?
You are changing your copy of the structure values, not the original.

Hope this helps
Jay

"Dennis" <Dennis@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:30779613-D99E-4EEB-938E-777319F0666B@xxxxxxxxxxxxxxxx
| If I pass a structure byval that contains both reference and value types,
| what exactly am I passing and if I change a structure field in my
function,
| is the structure field in the calling procedure changed also?
| --
| Dennis in Houston
|
|
| "Jay B. Harlow [MVP - Outlook]" wrote:
|
| > Mike,
| > In addition to the other comments.
| >
| > I would define the function as:
| >
| > | Public Function CleanSomething(ByVal value As String) As String
| >
| > To help ensure the "fastest" possible function! Remember that ByVal &
ByRef
| > refer to how parameters are passed, while Reference Type & Value Type
refer
| > to how values are stored.
| >
| > ByVal passes a copy of the variable as the parameter.
| > ByRef passes a reference to the variable as the parameter.
| >
| > Reference Types exist on the heap, a variable holds a reference to the
| > actual object on the heap.
| > Value Types exist on the stack or nested inside another object, a
variable
| > holds the actual value.
| >
| >
| > String is a Reference type, which means that a String variable or
parameter
| > holds a reference to the actual string object on the Heap. If you pass a
| > String ByRef to a routine, you are passing a reference to the variable
that
| > holds a reference to the actual string object on the heap. In other
words a
| > reference to a reference to an object. If you pass a String ByVal you
| > passing the reference itself. In other words a reference to an object.
| >
| > I would expect ByRef String to be slightly slower as you are
dereferencing a
| > reference each time you want to access the String's value.
| >
| > When you define your function "As String" you are receiving a copy of
the
| > reference to the actual string object on the heap. There is only one
| > instance of the String on the heap.
| >
| > Hope this helps
| > Jay
| >
| > "Mike Labosh" <mlabosh@xxxxxxxxxxx> wrote in message
| > news:uHx7kbDeFHA.228@xxxxxxxxxxxxxxxxxxxxxxx
| > | >I would first suggest that you use a StringBuilder, rather than
Strings
| > for
| > | >heavy string manipulation.
| > |
| > | Actually, most of the stuff uses Regex's. But I do use StringBuilder
| > where
| > | I can. StringBuilder let me do one of our export batches in half the
time
| > | it used to take :):):)
| > |
| > | > Second, what is your function returning? If it returns a Reference
Type,
| > | > then you are only getting a copy of the pointer to the reference
type,
| > not
| > | > a copy of the reference type itself.
| > |
| > | Pretty much all the method prototypes in this class look like this:
| > |
| > | Public Function CleanSomething(ByRef value As String) As String
| > |
| > | There is one method that returns a Structure, also.
| > |
| > | I just want to make sure I'm returning the return value ByRef for
greater
| > | speed / efficiency.
| > |
| > | --
| > | Peace & happy computing,
| > |
| > | Mike Labosh, MCSD
| > |
| > | "Mr. McKittrick, after very careful consideration, I have
| > | come to the conclusion that this new system SUCKS."
| > | -- General Barringer, "War Games"
| > |
| > |
| >
| >
| >


.

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