Array Bitwise XOR Byte, Sbyte For Nullable Structure

Integer

This is a core type in VB.NET programs. It is the default numeric type. Usually loops use the Integer type for their indexes.

Integer details

Because it is everywhere, it is worthwhile to explore this .NET type in more depth. This is a 4-byte numeric type. We can measure its memory usage in an array.

An example

We test some important parts of the Integer type. The Integer is a Structure, but we think of it as a low-level native type in VB.NET.

Part 1 An Integer is declared with a Dim statement. It can store positive values, such as 1, and negative values, such as -1.

Part 2 Expressions in VB.NET do not change the value of variables—unless the variables are assigned to the expression result.

Part 3 In this language, an Integer is mapped to the System.Int32 type. It has a range of over 4 billion values.

Part 4 We allocate an Integer array. We determine that each Integer occupies 4 bytes (all data is stored within the array).

Module Module1
    Sub Main()
        ' Part 1: specify an Integer Dim.
        Dim number As Integer = 1
        Console.WriteLine(number)
        number = -1
        Console.WriteLine(number)

        ' Part 2: use expressions.
        Console.WriteLine(number = -1)
        Console.WriteLine(number + 100)

        ' Part 3: get type and maximum and minimum values.
        Console.WriteLine(number.GetType())
        Console.WriteLine(Integer.MaxValue)
        Console.WriteLine(Integer.MinValue)

        ' Part 4: compute memory per Integer.
        Dim bytes1 = GC.GetTotalMemory(False)
        Dim array(100000) As Integer
        array(0) = 1
        Dim bytes2 = GC.GetTotalMemory(False)
        Console.WriteLine((bytes2 - bytes1) / 100000)
    End Sub
End Module1
-1
True
99
System.Int32
2147483647
-2147483648
4.00032

Some important values

It is worthwhile to emphasize the minimum and maximum values for an integer. Often our programs will access Integer.MinValue and MaxValue for bounds.

Mapped to:  System.Int32
 MinValue:  -2147483648
 MaxValue:   2147483647

Nullable Integer

An Integer is a value type, so it cannot be set to Nothing. But we can wrap an Integer in a Nullable Structure, with special syntax in VB.NET.

And The nullable structure can be set to Nothing. We can use GetValueOrDefault to safely get the underlying numeric value (if any).

Module Module1

    Sub Main()
        ' A nullable Integer can be a numeric value, or Nothing.
        Dim test As Integer? = 100
        Console.WriteLine("GETVALUEORDEFAULT: {0}", test.GetValueOrDefault())

        test = Nothing
        Console.WriteLine("GETVALUEORDEFAULT: {0}", test.GetValueOrDefault())
    End Sub

End ModuleGETVALUEORDEFAULT: 100
GETVALUEORDEFAULT: 0

Loops

As a fundamental type, the Integer is used in For loops as an index. In languages, the integer type (int) is usually optimized for performance.

Thus In most programs, the int as a local variable is the fastest. It is worth keeping int for loop indexes.

A summary

Integer is a fundamental type in VB.NET programs. It is mapped to System.Int32, which makes it precisely equivalent, in the C# language, to int. It requires four bytes of memory.

Integer has well-known lower and upper values. It has low-level optimizations for performance. This core type is worth researching. It is used throughout software projects.