Lesson 8: Data Types in VB2019

In our daily life, we have to deal with all kinds of information and data. For example, we need to deal with data like names, money, phone numbers, addresses, dates, and more. Similarly, in Visual Basic 2019, we have to deal with all sorts of data, some of them can be mathematically calculated while some are in the form of text or other non-numeric forms.

8.1 Understanding Data Types

Visual Basic 2019 classifies information into two major data types: numeric data types and non-numeric data types. Choosing the appropriate data type is crucial for efficient memory usage and accurate calculations.

8.1.1 Numeric Data Types

In Visual Basic 2019, numeric data are classified into seven types based on the range of values they can store. Numeric data that involve round figures are classified as Integer or Long integer. Data that require high precision calculation are classified as single and double precision data types (also called floating point numbers). Numeric data that involve money are classified as currency data types. Lastly, data that require more precision and involve many decimal points are classified as decimal data types.

8.1.2 Non-numeric Data Types

In Visual Basic 2019, non-numeric data types are data that cannot be calculated using standard arithmetic operators. The non-numeric data comprises text or string data types, the Date data types, the Boolean data types that store only two values (true or false), Object data type and Variant data type.

8.1.3 Suffixes for Literals

In Visual Basic 2019, we can add a suffix behind a literal so that Visual Basic can handle the calculations more accurately. For example, we can use num=1.3089! for a single precision data type, num=1.3089# for a double precision data type, num=130890& to indicate long integer data type and num=1.3089@ to indicate currency data type.

In addition, we need to enclose string literals within two quotations and date and time literals within two # signs. Strings can contain any characters, including numbers. Examples:

' String literals
Dim memberName As String = "Turban, John."
Dim telNumber As String = "1800-900-888-777"

' Date literals
Dim lastDay As Date = #31-Dec-2024#
Dim expTime As Date = #12:00 am#

' Numeric literals with suffixes
Dim population As Long = 7800000000&
Dim pi As Double = 3.1415926535#
Dim price As Currency = 19.99@

8.2 Performing Operations on Data

When VB2019 performs operations using arithmetic operators, it needs to understand the data types. It can perform mathematical operations on data of numeric nature but not a mix of numeric data and non-numeric data.

8.2.1 Adding Numbers

Adding two numbers is a valid operation. VB2019 will perform the arithmetic addition.

Private Sub BtnCompute_Click(sender As Object, e As EventArgs) Handles MyBase.Load
    ' Adding two numbers
    MsgBox(10 + 20.5)
End Sub

8.2.2 Adding a Number and a String

Adding a number to a string is invalid and causes a runtime error. VB2019 cannot perform arithmetic operations on mixed data types.

Private Sub BtnCompute_Click(sender As Object, e As EventArgs) Handles MyBase.Load
    ' Attempt to add a number and a string
    MsgBox(10 + "John")
End Sub

8.2.3 Concatenating Strings

Concatenating two strings is a valid operation. You can use either the + operator or the & operator for string concatenation.

Private Sub BtnCompute_Click(sender As Object, e As EventArgs) Handles MyBase.Load
    ' Concatenate two strings
    MsgBox("George" + " John")
    
    ' Alternative using & operator
    MsgBox("George" & " John")
End Sub

Next Lesson

Ready to learn about variables and constants? Continue to Lesson 9: Variables and Constants.

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