Random Access Fundamentals

[RichardN]

As a VB refugee I am having some problems understanding the fundamentals of random access read/write operations in B4A.

In VB I would construct a user-defined data type including fixed-length strings that would always give rise to a database divisable by the record-length. I can't understand how to do this in B4A.

A singlerecord might be:

varInt
varBoolean
varFloat
varString (maxlen 10)
varString (maxlen 30)

Q. How are the variables initialised in B4A to give a fixed length record?
Q. How is such a record written or read ?
Q. How is the number of such records determined when opening such a database?

I can't find an example in the documentation. Any chance of a short code sample that demonstrates the above ?

Thanks R

 

[Erel]

Do you want to save the data in a SQL database? If yes then you should use the SQL library:
http://www.b4x.com/forum/basic4android-getting-started-tutorials/6736-sql-tutorial.html
DBUtils - Android databases are now simple!
Simple example that uses DBUtils to display a table: http://www.b4x.com/forum/basic4andr...ls/8655-two-dimensional-database-reports.html

If you want to write the data to a file directly then you should use RandomAccessFile: Basic4android - RandomAccessFile
RandomAccessFile was updated several days ago and it can now save a custom type:
RandomAccessFile - V1.10 - Read/Write objects

You can declare custom types with the Type keyword.
Strings cannot be limited to a fixed size.

 

[RichardN]

Thanks very much Erel. In that case SQL is the way ahead.