Dynamically loaded functions crash

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1 total messages Started by Lawerence McHugh Tue, 02 Nov 1999 00:00

#1519

Author: Lawerence McHugh
Date: Tue, 02 Nov 1999 00:00

54 lines
2118 bytes

I am using C++ builder 3 to interface to a database via a dynamically loaded
DLL. Can anyone explain why the program crashes if I do not allocate local
storage in the a module that is not used. for example this code crashes out
with an memory access error.


void __fastcall TForm1::Callit(TObject *Sender);
{

hLib = LoadLibrary("C:\\Program Files\\Goldmine\\gm4s32.dll");
if( hLib ){
// Get address
fnGMW_DB_Append GMW_DB_Append = (fnGMW_DB_Append)
etProcAddress( (HINSTANCE) hLib,"GMW_DB_Append");

// pArea & szBuf are public members
pArea = GMW_DB_Open( "OPMGR" );

  if(pArea)
    {

         if( GMW_DB_Append( pArea, szBuf )!= 0) {
          GMW_DB_Unlock(pArea);
            }
 }}}


however if I add  char store[1000] in the module all works fine.

void __fastcall TForm1::Callit(TObject *Sender);
{
char store[1000]

hLib = LoadLibrary("C:\\Program Files\\Goldmine\\gm4s32.dll");
if( hLib ){
// Get address
fnGMW_DB_Append GMW_DB_Append = (fnGMW_DB_Append)
etProcAddress( (HINSTANCE) hLib,"GMW_DB_Append");

// pArea & szBuf are public members
pArea = GMW_DB_Open( "OPMGR" );

  if(pArea)
    {

         if( GMW_DB_Append( pArea, szBuf )!= 0) {
          GMW_DB_Unlock(pArea);
            }
 }}}

I don't want to leave the program like this as I cannot understand what is
happening.  The more calls I make to functions in the DLL I need to increase
the size of store. I'm sure there is a simple explanation. possibly I'm
doing something stupid can anyone point me in the right direction?

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