Structures in Visual Basic

Value types: copied on assignment, methods and all.

Dim origin As New Point
Dim peak As New Point With {.X = 3.0, .Y = 4.0}
Console.WriteLine(origin.DistanceTo(peak))

Dim copy = peak
copy.X = 99.0
Console.WriteLine($"value copy left peak.X at {peak.X}")

Structure Point
    Public X As Double
    Public Y As Double

    Public Function DistanceTo(other As Point) As Double
        Dim dx = X - other.X
        Dim dy = Y - other.Y
        Return Math.Sqrt(dx * dx + dy * dy)
    End Function
End Structure

How it works

1. Structure members live inline — no heap allocation per point.
2. With {.X = 3.0} fills fields as the value is made.
3. Assigning copies the whole value: mutating copy leaves peak alone.

Keywords and builtins used here

• Dim
• DistanceTo
• Double
• End
• Function
• New
• Point
• Public
• Return
• Structure
• With

The run, in numbers

Lines

18

Characters to type

416

Tokens

104

Three-star pace

85 tpm

At the three-star pace of 85 tokens a minute, this run takes about 73 seconds.

Type this snippet

Step 1 of 3 in Value types, step 19 of 29 in Language basics.

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