See below some functions declarations for Visual Basic.Frequently Asked Question:Q: Each time I use the compress function I get the -5 error (not enough   room in the output buffer).A: Make sure that the length of the compressed buffer is passed by   reference ("as any"), not by value ("as long"). Also check that   before the call of compress this length is equal to the total size of   the compressed buffer and not zero.From: "Jon Caruana" <jon-net@usa.net>Subject: Re: How to port zlib declares to vb?Date: Mon, 28 Oct 1996 18:33:03 -0600Got the answer! (I haven't had time to check this but it's what I got, andlooks correct):He has the following routines working:        compress        uncompress        gzopen        gzwrite        gzread        gzcloseDeclares follow: (Quoted from Carlos Rios <c_rios@sonda.cl>, in Vb4 form)#If Win16 Then   'Use Win16 calls.Declare Function compress Lib "ZLIB.DLL" (ByVal compr As        String, comprLen As Any, ByVal buf As String, ByVal buflen        As Long) As IntegerDeclare Function uncompress Lib "ZLIB.DLL" (ByVal uncompr        As String, uncomprLen As Any, ByVal compr As String, ByVal        lcompr As Long) As IntegerDeclare Function gzopen Lib "ZLIB.DLL" (ByVal filePath As        String, ByVal mode As String) As LongDeclare Function gzread Lib "ZLIB.DLL" (ByVal file As        Long, ByVal uncompr As String, ByVal uncomprLen As Integer)        As IntegerDeclare Function gzwrite Lib "ZLIB.DLL" (ByVal file As        Long, ByVal uncompr As String, ByVal uncomprLen As Integer)        As IntegerDeclare Function gzclose Lib "ZLIB.DLL" (ByVal file As        Long) As Integer#ElseDeclare Function compress Lib "ZLIB32.DLL"        (ByVal compr As String, comprLen As Any, ByVal buf As        String, ByVal buflen As Long) As IntegerDeclare Function uncompress Lib "ZLIB32.DLL"        (ByVal uncompr As String, uncomprLen As Any, ByVal compr As        String, ByVal lcompr As Long) As LongDeclare Function gzopen Lib "ZLIB32.DLL"        (ByVal file As String, ByVal mode As String) As LongDeclare Function gzread Lib "ZLIB32.DLL"        (ByVal file As Long, ByVal uncompr As String, ByVal        uncomprLen As Long) As LongDeclare Function gzwrite Lib "ZLIB32.DLL"        (ByVal file As Long, ByVal uncompr As String, ByVal        uncomprLen As Long) As LongDeclare Function gzclose Lib "ZLIB32.DLL"        (ByVal file As Long) As Long#End If-Jon Caruanajon-net@usa.netMicrosoft Sitebuilder Network Level 1 Member - HTML Writer's Guild MemberHere is another example from Michael <michael_borgsys@hotmail.com> that hesays conforms to the VB guidelines, and that solves the problem of notknowing the uncompressed size by storing it at the end of the file:'Calling the functions:'bracket meaning: <parameter> [optional] {Range of possible values}'Call subCompressFile(<path with filename to compress> [, <path withfilename to write to>, [level of compression {1..9}]])'Call subUncompressFile(<path with filename to compress>)Option ExplicitPrivate lngpvtPcnSml As Long 'Stores value for 'lngPercentSmaller'Private Const SUCCESS As Long = 0Private Const strFilExt As String = ".cpr"Private Declare Function lngfncCpr Lib "zlib.dll" Alias "compress2" (ByRefdest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long,ByVal level As Integer) As LongPrivate Declare Function lngfncUcp Lib "zlib.dll" Alias "uncompress" (ByRefdest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long)As LongPublic Sub subCompressFile(ByVal strargOriFilPth As String, Optional ByValstrargCprFilPth As String, Optional ByVal intLvl As Integer = 9)    Dim strCprPth As String    Dim lngOriSiz As Long    Dim lngCprSiz As Long    Dim bytaryOri() As Byte    Dim bytaryCpr() As Byte    lngOriSiz = FileLen(strargOriFilPth)    ReDim bytaryOri(lngOriSiz - 1)    Open strargOriFilPth For Binary Access Read As #1        Get #1, , bytaryOri()    Close #1    strCprPth = IIf(strargCprFilPth = "", strargOriFilPth, strargCprFilPth)'Select file path and name    strCprPth = strCprPth & IIf(Right(strCprPth, Len(strFilExt)) =strFilExt, "", strFilExt) 'Add file extension if not exists    lngCprSiz = (lngOriSiz * 1.01) + 12 'Compression needs temporary a bitmore space then original file size    ReDim bytaryCpr(lngCprSiz - 1)    If lngfncCpr(bytaryCpr(0), lngCprSiz, bytaryOri(0), lngOriSiz, intLvl) =SUCCESS Then        lngpvtPcnSml = (1# - (lngCprSiz / lngOriSiz)) * 100        ReDim Preserve bytaryCpr(lngCprSiz - 1)        Open strCprPth For Binary Access Write As #1            Put #1, , bytaryCpr()            Put #1, , lngOriSiz 'Add the the original size value to the end(last 4 bytes)        Close #1    Else        MsgBox "Compression error"    End If    Erase bytaryCpr    Erase bytaryOriEnd SubPublic Sub subUncompressFile(ByVal strargFilPth As String)    Dim bytaryCpr() As Byte    Dim bytaryOri() As Byte    Dim lngOriSiz As Long    Dim lngCprSiz As Long    Dim strOriPth As String    lngCprSiz = FileLen(strargFilPth)    ReDim bytaryCpr(lngCprSiz - 1)    Open strargFilPth For Binary Access Read As #1        Get #1, , bytaryCpr()    Close #1    'Read the original file size value:    lngOriSiz = bytaryCpr(lngCprSiz - 1) * (2 ^ 24) _              + bytaryCpr(lngCprSiz - 2) * (2 ^ 16) _              + bytaryCpr(lngCprSiz - 3) * (2 ^ 8) _              + bytaryCpr(lngCprSiz - 4)    ReDim Preserve bytaryCpr(lngCprSiz - 5) 'Cut of the original size value    ReDim bytaryOri(lngOriSiz - 1)    If lngfncUcp(bytaryOri(0), lngOriSiz, bytaryCpr(0), lngCprSiz) = SUCCESSThen        strOriPth = Left(strargFilPth, Len(strargFilPth) - Len(strFilExt))        Open strOriPth For Binary Access Write As #1            Put #1, , bytaryOri()        Close #1    Else        MsgBox "Uncompression error"    End If    Erase bytaryCpr    Erase bytaryOriEnd SubPublic Property Get lngPercentSmaller() As Long    lngPercentSmaller = lngpvtPcnSmlEnd Property