Android Question String in to binary file

[Claudio57]

I'm new in B4A. I was pretty good at VB6.
I have a problem with binary files.
I can't write a string to a binary file.
I can't find a method to write a string.
How to?

Martina

 

[Beja]

can you post a simple example in vb6 that you want to port to b4a?

 

[Erel]

How are you writing the binary file? With RandomAccessFile?

How do you want the string to be written?

You can use raf.WriteObject to write strings.

 

[Claudio57]

Hi Erel,
I do not know English and use the Google translator . I have a big problem. I have to make an application that works with binary files. Must work with binary files because the files are also managed by Windows applications written in VB6 .
In VB6 type is declared like this:

Type Classification
Name As String * 15
Points As Integer
Goal As Integer
end Type

and then there is an array like this:

Public Cla ( 1 To 20 ) As Classification

This array is saved in a binary file with a for next:

For i = 1 To 20
Put # 1 , Cla ( i)
Next i

and when it should be read:

For i = 1 To 20
Get # 5 , Cla ( i)
Next i

I tried to do it in B4A but I can not make it work:

Type Classification ( Name As String , Value As Short , goal As Short )

but when I write I do not know what to do. I tried with:

Dim a As Classification
a.initialize
a.name ="Juventus"
a.points=22
a.goal=19
raf.Initialize ( File.DirRootExternal , " Class.gsc " , False)
raf.WriteObject (a, False , raf.CurrentPosition )

Please if you can help me. Maybe show me a tutorial on the RAF.

 

[Erel]

In that case you cannot use raf.WriteObject.

Is the length of Name always 15 bytes (or characters)?

 

[Claudio57]

Characters. Yes. I use:
a(i).name=a(i).name & string$(15-len(a(i).name), " ")

 

[Erel]

Which encoding are you using in your VB6 app? Are there any non-ASCII characters?

If for example you are using UTF8 with non-ASCII characters then the size of this structure will not be constant.

 

[Claudio57]

The size of structure is constant.

 

[Erel]

I understand it. You should however know which encoding is used.

I assume that it is ASCII. What happens if the string is shorter than 15 characters?

You can do something like:

Sub WriteClarification(raf As RandomAccessFile, c As ClarificationType)
 Dim b() As Byte = c.Name.GetBytes("ASCII")
 raf.WriteBytes(b, 0, b.Length, raf.CurrentPosition)
 for i = b.Length To 14
  raf.WriteByte(0, raf.CurrentPosition)
 Next
 raf.WriteInt(c.Point, raf.CurrentPosition)
 raf.WriteInt(c.Goal, raf.CurrentPosition)
End Sub

 

[Claudio57]

Thanks Erel. Tomorrow I try and tell you.

 

[Claudio57]

Ok, works. I now wish I had an example of how to read the same record.
Thank you Erel.

 

[LucaMs]

I'm new in B4A. I was pretty good at VB6.
I have a problem with binary files.
I can't write a string to a binary file.
I can't find a method to write a string.
How to?

Martina

Also I have a question ... Claudio57 or Martina90? But do not do it... ma non la faccio!

 

[Claudio57]

Erel

I understand it. You should however know which encoding is used.

I assume that it is ASCII. What happens if the string is shorter than 15 characters?

You can do something like:

Sub WriteClarification(raf As RandomAccessFile, c As ClarificationType)
 Dim b() As Byte = c.Name.GetBytes("ASCII")
 raf.WriteBytes(b, 0, b.Length, raf.CurrentPosition)
 for i = b.Length To 14
  raf.WriteByte(0, raf.CurrentPosition)
 Next
 raf.WriteInt(c.Point, raf.CurrentPosition)
 raf.WriteInt(c.Goal, raf.CurrentPosition)
End Sub

Hi Erel,
the length of the file with only one record is 34. It should be 19 (15 Name, 2 Point and 2 Goal). Why?

 

[Claudio57]

Thanks Erel. There are successful. Now it works. I write and read.
Without your help I would have never succeeded.

 

[Claudio57]

I have a binary file written in VB6. There are some numbers that I wrote as an integer.
Now when I read them in B4A call them as Short. These values do not match. Instead of 1 reads 256 instead of 2 512 etc. How do I fix?

 

[LucaMs]

I have a binary file written in VB6. There are some numbers that I wrote as an integer.
Now when I read them in B4A call them as Short. These values do not match. Instead of 1 reads 256 instead of 2 512 etc. How do I fix?

Avevo fatto delle prove, giorni fà... guarda se ti sono utili.

Ciao

 

[Claudio57]

Ciao. Mi da errore qua
Private mByteConverter As ByteConverter

 

[LucaMs]

Ciao. Mi da errore qua
Private mByteConverter As ByteConverter

Ti manca quella libreria, ByteConverter di Agraham, ecco il link

 

[Claudio57]

Il tuo esempio è molto bello e mi da anche degli spunti utili però il mio problema è che i file che ho scritti in VB6 devono essere gestiti sia da PC (Windows) che da Smartphone. I dati integer scritti nel file binario occupano 2 Bytes, gli Int di B4A 4, allora in B4A ho definito Short i tipi relativi ai punti etc. Quando vado a leggerli però mi ritorna dei valori diversi da quelli scritti. Non ho capito perchè e che cosa devo fare.

 

[Claudio57]

I still have this big problem: I want to read integers written in binary file from VB6 and I want to write them B4A to read it in VB6.
How to?