Software Development

  Lecture Notes

Programming Standards - Naming Controls

Introduction

Why Bother With Standards

Naming Controls

Introduction

Objectives

This guide  will help you to: -  

·  understand the need for programming standards

·  understand how to name VB controls properly

Why Bother with Standards

To read and understand program code easily, it must be written consistently to conform to agreed coding standards. This means...

• naming controls and variables properly
• commenting code
• declaring variables properly
• always specifying variable datatypes
• defining variables with the smallest possible scope
• using uppercase letters for constants
• code indentation

Programmers familiar with the coding standards can understand their own code and other programmer's code much more easily if the code adheres to the standards. For a software development company, adhering to a standards ensures consistency, uniform development and ultimately leads to lower development and maintenance costs.

Naming Controls

For a control name to be meaningful in Visual Basic, the name must immediately convey at least two essential pieces of information about the control:

• what it is

• what it is used for

If we look at some of VB's default control names...

Text1, Command1, Option1

...for each one we can tell from the name - what it is, but we cannot tell - what it is used for.

Naming conventions can help us with this. To name a control we use a three letter prefix for the first part of the name, then for the rest of the name we use something descriptive: - something that describes what the control is used for.

Here are some examples.

txtFirstName	' this is a textbox for a user to type in their first name
txtLastName	' this is a textbox for a user to type in their last name
cmdClose	' this is a command button for closing the program

Of course, to understand and use naming conventions for controls you need to know the three letter prefix for each control. Below is list of the prefixes for the more common controls.

So, when naming a control, you need to use the three letter prefix first, then the rest of the name should relate to the function of the control - it should describe something about it, so when you come across the name in your code, you know exactly which control it is.

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Here as some more examples

Examples:

1. What would you name command button that ends a program when clicked?

   cmdExit    or    cmdEnd    or something similar

2. What would you name a text box that expects a user to type in their first age?

   txtAge    or something similar

3. What would you name a label that displays the height of a room

   lblRoomHeight    or something similar

Can you remember how to change the names of controls?  You have to select that control and then type in the name you want in the properties window.  Look at the picture below showing the name of a command button being set to cmdSubmit.

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Activity B

What do you think I named the command buttons shown in the picture?     Answer   What about the controls on the form below?       Answer

One final point on naming controls. You only need to name the controls that you are going to refer to in code. For example, quite often you will have labels on your form. Most of the times these labels will be static and will never change, so it is pointless naming them. Of course, if you do have a label that the program needs changes dynamically, then you need to name it properly. Frames are similar. You only need to name them if you refer to them in the code.

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Activity C

Here is part of a program that calculates the area of a rectangular lawn. Can you guess the names I used for the... the two textboxes the picture box the frame Answer

 

Fini