Visual Basic

Visual Basics: VB, VBA, MS Office

This is a collection of related notes. I will not be updating them as I'm not using the platform at this time.

They're out of order, but there's a lot of potentially useful information in here. Maybe I'll compile it into a short ebook at some point.

Comparison Shopping for Toilet Paper, in multiple computer languages.

It's hard to concentrate when you're tired and cranky, so I wasted some time writing a simple calculator in several different languages.

That 70s Computer: The People's Computer Company

The first computer book I read was "Teach Yourself Basic" by Bob Albrecht. It wasn't a really good book - at least not for a child - but there it was. Mr.

MS Access: Printing a "Dictionary Header" on a Report

I wanted to print a report that indicated the first and last item on each page, just like a dictionary has. You know: "Azeri - Babcock", "Milk - Minder". It makes it easier to flip through printouts.

This is how to do it. It will put the range in the footer. I haven't figured out how to do one in the header, which is what I originally wanted, but found too difficult to do. (There is probably a way.)

First, take your report, and add an unbound field to your report. Rename it to "Range". See the picture below.

MS Access: A Hack to Print Blank Rows in a Report

This is a way to insert empty or empty-like rows into a list of "seats" that contains not only reservations, but a number saying how many seats a group of people have. If the number is greater than the number of seats, this adds new blank rows for empty seats.

Sub insertBlankRows()
    Dim dbs As Database, qdf As QueryDef, strSQL As String
    Dim rst As Recordset
    
    Set dbs = CurrentDb
    strSQL = "SELECT tblSeats.OrganizationId, [MaxOfSeats]-Count([OrganizationId]) AS Difference, " & _

Novice's Notebook

This is a repository of "novice" articles, written with the intent of driving more traffic to the site, and getting more ad clicks. It's pretty crass, I know, but the information may be very useful.

Learn VisualBasic.NET with Me: (s)locate files on a disk with VBA

This is a class that will help you find files on the disk, without hitting the disk too much. It's a simplified unix "slocate" library. The first time you use it, it creates an index of all the files on the drive. (Subsequent uses update the file when a day passes.) The index is loaded into memory, and searched with regular expressions.

Learn VisualBasic.NET with Me: running the code

This blog entry doesn't discuss any code, because I ended up doing very little work on the software. I was busy running it, and the app tends to take over the UI, making programing difficult. For the most part, it functioned as expected, but a couple things changed in how I actually used it.

I added a text box to restrict scanning for MXD files to a subdirectory. This new feature allowed me to set the source root and destination root directories, and then type the subdirectory to be processed. The text box could also be left blank.

I used this feature a lot.

Learn VisualBasic.NET with Me: crash woes, threading template

It was looking pretty grim for the file copier. The main problems were twofold:

First, the app sometimes crashed on bad data. The Windows crash-reporting dialog box came up, and all work stopped until it was dismissed.

Learn VisualBasic.NET with Me: rubber meets road

I'm finally running that program I've been writing. For the most part, it was "bug free" inasmuch as the different parts ran their test cases correctly, and it runs fine on a small subset of data. Of course, it's not like I ever really learned the system completely, so there are a lot of situations that I'm not handling (or even aware of). Moreover, because the users probably don't use all the features of the software, it's not likely that a complete solution is necessary. No project is debugged "enough" until it operates on real data, in a real situation.

Learn VisualBasic.NET with Me: recursion

It's going to be a lesson about recursion. It's strictly beginner level.

I don't have any code today, because I was working the polls yesterday, and spent most of today's worktime tuning that file copier. I hit a big problem because of some confusing, mis-coded loops. Here's the scenario in pseudocode (I don't want to fire up the Windows box just to get this code).

for each item in collectionA
    if type of item is Layer then
        processLayer item
    else if type of item is LayerGroup then
        for each subItem in item

Learn VisualBasic.NET with Me: is a time within a time span?

This article discusses debugging a function by rewriting the code.

I'm not sure what I did wrong here, but, my first version of this function didn't work. The function returns true if the current time is withing two time spans. This code was written in a rush, without really thinking about how to do it, because it seemed pretty straightforward. The code, however, was a mess (and embarassing).

    Private Function itIsTimeToWork() As Boolean
        ' Get the two start and end times, and determine if we're within 
        ' the intervals.

Learn VisualBasic.NET with Me: spinning my wheels, animating an image with the timer

For some reason or other, I didn't get an email response from the client on this gig*, and the week was hectic, so instead, I just worked on making the UI a little nicer. VB has a lot of controls, including a background threader, some standard dialogs, and a serial port. This is giving me a real "Rip Van Winkle" feeling, having been over in Unixville for a while.

(* It was lost in my huge email pile. My bad. No matters... the program got a nice facelift.)

Some COM and .NET Notes

This document explains some terminology used on other pags.

ActiveX
A technology layered on OLE that supports a method, IDispatch(), that executes method calls by name (by a string argument). IDispatch() solved the problem of scripting languages being late bound, and not able to handle multiple interfaces. ActiveX also covered other technical things, but the IDispatch feature is relevant to this topic.
Assemblies
A group of classes. The classes generally work together, and form a namespace. Analagous to a Java package. The .NET assemblies are analagous to the Java class libraries.
CLR, Common Language Runtime
A "virtual machine" that executes programs coded in CL, a platform-neutral assembly language produced by compilers. The CLR is also called a "managed environment" because the virtual machine takes care of many runtime issues like allocating memory.
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