Option Explicit (1 Viewer)

[Ilovexfiles]

Im new to vba. Im halfway through building my database and have realized how important "option explicit" is, which I have not been using, and am still trying to grasp the concept of.

I'm thinking of turning it on now to use moving forward and figure out along the way, or is it imperative that I add it to the coding ive already completed?
Thanks

 

[Galaxiom]

Add it everywhere. Then any error in your variable names will be thrown at Compile time instead of waiting until it is run.

You can probably use a Find and Replace across the whole project to change

Option Compare Database

to

Option Explicit
Option Compare Database

 

[Orthodox Dave]

You need to do what Galaxiom says for all existing code. The statement doesn't have to be put into every individual procedure, just at the top of the page of each module for which you have code - under Option Compare Database as in

Option Compare Database
Option Explicit

Then if you set the VBA Tools as in the attached picture, it will be set automatically for all future code you write.

 

[gemma-the-husky]

if you do not set "option explicit" then all undefined variables are created as variant types.

Having "rogue" variable makes debugging hard, and can cause unwanted side effevts - as also can incorrect variable typing.

I cannot think of any reason not to require variable calculation. It's probably only an option not to have it, because of the historical links to the original Basic language.

 

[Ilovexfiles]

Thank you, I just set the default to Option Explicit.
I have entered declared variables at the top of module. Do I need to add it to each procedure too? Also the Integers below are actually drop downs.

Option Explicit
Option Compare Database

Dim AdmitDate As Date
Dim AdmitTime As Date
Dim PhysicalorTc As Integer
Dim NeworCds As Integer
Dim ExitDate As Date
Dim ExitTime As Date
Dim Placement As Integer

---

Private Sub ExitDate_BeforeUpdate(Cancel As Integer)
If Me![ExitDate] < Me![AdmitDate] Then
MsgBox "Exit Date cannot be earlier than Admit Date!"
Cancel = True
End If
End Sub

 

[Orthodox Dave]

I have entered declared variables at the top of module. Do I need to add it to each procedure too? Also the Integers below are actually drop downs.

Er ... oh I see. You don't declare variables for items on forms that you are referring to. For example:

If Me![ExitDate] < Me![AdmitDate]

The above(ExitDate and AdmitDate) are not "Variables", but controls on a form.

Have I read you right?

 

[Ilovexfiles]

Thank you

 

[Frothingslosh]

Okay, a quick lesson on variable scope.

If you declare variables in the top section of a module, before any procedures are defined, then they have module-level scope. This means that these variables are visible and usable for all procedures in that module.

If you declare them inside a given procedure, then they are local variables, meaning they can only be seen and/or used by the procedure where they were defined.

If you declare them at the start of the module (keep in mind that the Option statements still need to be first) but add the 'Public' or 'Global' keywords to the declaration, then they're actually available throughout the application. (Public is available in more places, so if you need to use these, get used to using that one.)

 

[Ilovexfiles]

Er ... oh I see. You don't declare variables for items on forms that you are referring to. For example:

The above(ExitDate and AdmitDate) are not "Variables", but controls on a form.

Have I read you right?

Hi yes, I am referring to the "field names" in the code and have gotten compile errors everywhere stating: ""The member already exists in an object module from which this object module derives"

 

[Frothingslosh]

You really don't want to declare variables with the same names are your fields or controls. In fact, I'm about 99% certain that that is why you're getting the compile error.

Hell, I make a point of ensuring my controls don't even share their names with fields, and Access can generally handle that situation fine.

My first recommendation would be to delete or rem out all those declarations you made at the start of the form module. You only need to declare VARIABLES, not existing controls and fields.

 

[Frothingslosh]

Well, variables, constants, and the like.

 

[Cronk]

Hell, I make a point of ensuring my controls don't even share their names with fields, and Access can generally handle that situation fine.

Me too but I do make it such that it is easy to identify the control if I am referring to it in code.

Field name: LastName
Control name: txtLastName or cboLastName
Variable name: strLastName