Programming Tutorials

Converting between Data Types in VB.net

By: Steven Holzner in VB.net Tutorials on 2008-11-25  

Take a look at this code:

Option Strict On
Module Module1
    Sub Main()
        Dim dblData As Double
        Dim intData As Integer
        dblData = 3.14159
        intData = dblData
        System.Console.WriteLine("intData = " & Str(intData))
    End Sub

End Module

In this case, I've turned Option Strict on, which means that Visual Basic will not automatically convert data types when you assign a value of one type to a variable of another, so it'll have problems with the statement highlighted above, where I assign a double precision floating point variable to an integer variable. To fix this problem, I have to do a specific type conversion. I do this with the CInt function, which converts its argument to type Integer:

Option Strict On
Module Module1
    Sub Main()
        Dim dblData As Double
        Dim intData As Integer
        dblData = 3.14159
        intData = CInt(dblData)
        System.Console.WriteLine("intData = " & Str(intData))
    End Sub

End Module

When I run this code, I get this result-notice that the decimal places have been removed to make the value of pi into an integer:

intData =  3
Press any key to continue

Here's the list of conversion functions you can use:

• CBool- Convert to Bool data type.

• CByte- Convert to Byte data type.

• CChar- Convert to Char data type.

• CDate- Convert to Date data type.

• CDbl- Convert to Double data type.

• CDec- Convert to Decimal data type.

• CInt- Convert to Int data type.

• CLng- Convert to Long data type.

• CObj- Convert to Object type.

• CShort- Convert to Short data type.

• CSng- Convert to Single data type.

• CStr- Convert to String type.

If you can't remember the name of a particular conversion function, you also can use the CType function, which lets you specify a type to convert to. (This is useful if you're converting to a type that is not one of the simple types in the list above.):

Option Strict On
Module Module1
    Sub Main()
        Dim dblData As Double
        Dim intData As Integer
        dblData = 3.14159
        intData = CType(dblData, Integer)
        System.Console.WriteLine("intData = " & Str(intData))
    End Sub
End Module