How to declare a fixed-length string in VB.NET?

Question

How do i Declare a string like this:

Dim strBuff As String * 256

in VB.NET?

Answer 1

Use stringbuilder

'Declaration   
Dim S As New System.Text.StringBuilder(256, 256)
'Adding text
S.append("abc")
'Reading text
S.tostring

Answer 2

Dim a as string

a = ...

If a.length > theLength then

     a = Mid(a, 1, theLength)

End If

Answer 3

To write this VB 6 code:

Dim strBuff As String * 256

In VB.Net you can use something like:

Dim strBuff(256) As Char

Answer 4

This object can be defined as a structure with one constructor and two properties.

Public Structure FixedLengthString
     Dim mValue As String
     Dim mSize As Short

     Public Sub New(Size As Integer)
         mSize = Size
         mValue = New String(" ", mSize)
     End Sub

     Public Property Value As String
         Get
             Value = mValue
         End Get

         Set(value As String)
             If value.Length < mSize Then
                 mValue = value & New String(" ", mSize - value.Length)
             Else
                 mValue = value.Substring(0, mSize)
             End If
         End Set
     End Property
 End Structure

https://jdiazo.wordpress.com/2012/01/12/getting-rid-of-vb6-compatibility-references/

Answer 5

Try this:

    Dim strbuf As New String("A", 80)

Creates a 80 character string filled with "AAA...."'s

Here I read a 80 character string from a binary file:

    FileGet(1,strbuf)

reads 80 characters into strbuf...

Answer 6

It depends on what you intend to use the string for. If you are using it for file input and output, you might want to use a byte array to avoid encoding problems. In vb.net, A 256-character string may be more than 256 bytes.

Dim strBuff(256) as byte

You can use encoding to transfer from bytes to a string

Dim s As String
Dim b(256) As Byte
Dim enc As New System.Text.UTF8Encoding
...
s = enc.GetString(b)

You can assign 256 single-byte characters to a string if you need to use it to receive data, but the parameter passing may be different in vb.net than vb6.

s = New String(" ", 256)

Also, you can use vbFixedString. I'm not sure exactly what this does, however, because when you assign a string of different length to a variable declared this way, it becomes the new length.

<VBFixedString(6)> Public s As String
s = "1234567890" ' len(s) is now 10