Data Compression With Zlib
Version Compatibility: Visual Basic 6
The following module contains two public functions:
DataOrText: Either a byte array (1D) or a string
Key: Original size (required to uncompress) If not provided, the key will be embedded in the compressed data itself
Returns compressed byte array or string, respectively
Uncompress(DataOrText,Optional Byval Key)
Key: Original size. If not provided, Uncompress() will look for it in the compressed data.
Returns uncompressed byte array or string, respectively
In order to successfully uncompress compressed data, the underlying ZLib functions require the original size (of the uncompressed data.) To make things easier, these functions will automatically include this value in the compressed data so that you, the programmer, won't need to keep track of this information yourself. However, if you like, you can provide a Long variable to the Compress() function. This will tell the function to return it directly to you instead of adding it to the compressed data. But you must provide this value to the Uncompress() function or else it won't work.
Here's an example function:
Public Sub Example() Dim sTmp As String Dim lKey As Long sTmp = Compress("This is a test.") Debug.Print Len(sTmp), Len(Uncompress(sTmp)) sTmp = Compress("This is a test.", lKey) Debug.Print Len(sTmp), Len(Uncompress(sTmp, lKey)) sTmp = vbNullString End SubImmediate window example:
call example 25 15 21 15Anyway, I hope this is clear. If not, just follow the commented code =)
Instructions: Copy the declarations and code below and paste directly into your VB project.