Visual Basic

10th February 2017

What Is a Programming Language?

People express themselves using a language that has many words. Computers use a simple binary language like an electric circuit that consists of only 1s and 0s, with a 1 meaning “on” and a 0 meaning “off.”

A programming language acts as a translator between you and the computer. Rather than learning the computer’s native language (known as machine code), you can use a programming language to instruct the computer in a way that is easier to learn and understand.

The Basics of VB

Microsoft Visual BasicA specialized program known as a compiler takes the instructions written in the programming language and converts them to machine language. This means that as a Visual Basic programmer, you don’t have to understand what the computer is doing or how it does it. You just have to understand how the Visual Basic programming language works.

Visual Basic is a great starter programming language. Not only is it easy to learn, but many organisations use it extensively for their applications. If you are just starting to learn to develop applications it is a great language to start with.

The language you write and speak has structure: for example, a book has chapters with paragraphs that contain sentences consisting of words. Programs written in Visual Basic also have a structure: modules are like chapters, procedures are like paragraphs, and lines of code are like sentences.

When you speak or write, you use different categories of words, such as nouns or verbs. Each category is used according to a defined set of rules. In many ways, Visual Basic is much like the language that you use every day. Visual Basic also has rules that define how categories of words, known as programming elements, are used to write programs.

Programming elements in Visual Basic include statements, declarations, methods, operators, and keywords. As you complete the following lessons, you will learn more about these elements and how to use them.

Written and spoken language also has rules, or syntax, that defines the order of words in a sentence. Visual Basic also has syntax—at first it may look strange, but it is actually very simple. For example, to state “The maximum speed of my car is 70”, you would write:

Car.Speed.Maximum = 70

You can learn more about syntax on any of our range of Visual Basic Training Courses.  Built-in features in Visual Basic such as IntelliSense provide you with guidance in using the correct syntax when you write programs.

The Basics of Variables

Visual Basic StudioA variable in a programming language is similar to the way a variable works in math. If I have the equation x = 2 + y, I have two variables – x and y. These variables represent any number that can be placed in them. In the programming realm, we define a variable by a given name (for example strMyName) so that strMyName can store a value, like someone’s name, and later when we want to use that value we can call it up by using strMyName. It makes a lot of sense once you see a few simple examples.

In Visual Basic we define a variable name by using the keyword Dim.

Dim stands for “dimension” – which we have inherited from the early days of programming – it was used to define the dimensions of an array in the original implementation of BASIC, known as Dartmouth BASIC

When you define a variable, you also specify what type of data it is allowed to hold. Below is a list of all the different data types and what data they can hold.

The following table shows the Visual Basic data types, their supporting common language runtime types, their nominal storage allocation, and their value ranges.

Visual Basic type Nominal storage allocation Value range
Boolean Depends on implementing platform True or False
Byte 1 byte 0 through 255 (unsigned)
Char (single character) 2 bytes 0 through 65535 (unsigned)
Date 8 bytes 0:00:00 (midnight) on January 1, 0001 through 11:59:59 PM on December 31, 9999
Decimal 16 bytes 0 through +/-79,228,162,514,264,337,593,543,950,335 (+/-7.9…E+28) with no decimal point; 0 through +/-7.9228162514264337593543950335 with 28 places to the right of the decimal;

smallest nonzero number is +/-0.0000000000000000000000000001 (+/-1E-28)

Double (double-precision floating-point) 8 bytes -1.79769313486231570E+308 through -4.94065645841246544E-324 for negative values;

4.94065645841246544E-324 through 1.79769313486231570E+308 for positive values

Integer 4 bytes -2,147,483,648 through 2,147,483,647 (signed)
Long (long integer) 8 bytes -9,223,372,036,854,775,808 through 9,223,372,036,854,775,807 (9.2…E+18 ) (signed)
Object 4 bytes on 32-bit platform

8 bytes on 64-bit platform

Any type can be stored in a variable of type Object
SByte 1 byte -128 through 127 (signed)
Short (short integer) 2 bytes -32,768 through 32,767 (signed)
Single (single-precision floating-point) 4 bytes -3.4028235E+38 through -1.401298E-45 for negative values;

1.401298E-45 through 3.4028235E+38 for positive values

String (variable-length) Depends on implementing platform 0 to approximately 2 billion Unicode characters
UInteger 4 bytes 0 through 4,294,967,295 (unsigned)
ULong 8 bytes 0 through 18,446,744,073,709,551,615 (1.8…E+19 ) (unsigned)
User-Defined (structure) Depends on implementing platform Each member of the structure has a range determined by its data type and independent of the ranges of the other members
UShort 2 bytes 0 through 65,535 (unsigned)

In scientific notation, “E” refers to a power of 10. So 3.56E+2 signifies 3.56 x 102 or 356, and 3.56E-2 signifies 3.56 / 102 or 0.0356.