Call C DLL Functions in Perl

[sraghu_rs]

Dear Friends, I am writing to call the APIs (functions) in the C DLL using perl CPAN Module Win32::API. The code works fine in the case where API expects input variable as Long. When the API expects the input as char *, i am not getting expected results. In the below, API, (1) and (2) are working fine. But API (3) has input parametes as char *. The result is signed long. In the working case, the result should return value greater than zero. but i am getting result as zero. Could you please advice me, how to pass the value as char * (C datatype) to the API as expected by API. Thanks in advance. Regards, Rags

DLL : mydll.dll

1) API Syntax: long CurrentDate();

use Win32::API;
my $dec = Win32::API->new('mydll.dll', 'CurrentDate', '', 'L') or die 
+$^E;
my $rv_bstr = $dec->Call();
($sec,$min,$hour,$day,$month,$year) = localtime($rv_bstr);
# correct the date and month for humans
$year = 1900 + $year;
$month++;
printf "%02d/%02d/%02d %02d:%02d:%02d\n", $year, $month,$day, $hour, $
+min, $sec;

2) API Syntax: long GetVersion(char *pstrBuf, long lBuf);

use Win32::API;
my $dec = Win32::API->new('mydll.dll', 'GetVersion', 'PN', 'L') or die
+ $^E;
my $lpBuffer = " " x 64;
$return = $dec->Call($lpBuffer, 64);
print $lpBuffer;

3) API Syntax: long OpenConnection(char *strDataSource, char *strUser, char *strPwd);

use Win32::API;
my $dec = Win32::API->new('mydll.dll', 'OpenConnection', 'PPP', 'L') o
+r die $^E;
$strDatabase = "test";
$strLoginUser = "test";
$strLoginPwd = "test";
# converting to C String
$db = pack('a*x', $strDatabase);
$user = pack('a*x', $strLoginUser);
$pwd = pack('a*x', $strLoginPwd); 

$return = $dec->Call($db, $user, $pwd);
print $return;

[ikegami]

By the way,

($sec,$min,$hour,$day,$month,$year) = localtime($rv_bstr);
# correct the date and month for humans
$year = 1900 + $year;
$month++;
printf "%02d/%02d/%02d %02d:%02d:%02d\n", $year, $month,$day, $hour, $
+min, $sec;

can be written as

use POSIX qw( strftime );
print strftime "%Y/%m/%d %H:%M:%S\n", localtime($rv_bstr);

[ikegami]

Just like you did for (2).

$return = $dec->Call($strDatabase, $strLoginUser, $strLoginPwd);

That said, what you have amounts to strings terminated with two NULs, so it should work too.

[sraghu_rs]

@ikegami - Even after passing like that, it is not working.

[runrig]

Maybe "test" is not a valid database/user/password?

[ikegami]

I said as much, but it is the proper usage based on the information you posted. Is there anything to make you think it's a problem with how you call the function?