Why does this crash in XP but not in 98?

[kangolian]

Hi

My program needs to run on all versions of Windows from 95 to XP. It also needs to detect what type of OS it is running on, so I am using GetVersionEx for this.
Trouble is, my app runs fine on 98 but when I test it on XP it crashes with some kind of Access Violation.
Anyone got any ideas on how to get round this on XP?
Please help, I can't go any further with my app until I have solved this problem!
Here's my code:

#include <windows.h>
#include <iostream.h>

bool IsNTBased();

void main()
{
if ( IsNTBased() )
cout << &quot;Is NT based\n&quot;;
else
cout << &quot;Is not NT based\n&quot;;
}


bool IsNTBased()
// IsNTBased returns true if OS is NT based, e.g NT, 2000 or XP
// Processes: gathers OS info and checks platform id
// Returns: true if platform id indicates an NT based OS, false otherwise
{

OSVERSIONINFO * osinfo; // os version info structure pointer
GetVersionEx( osinfo ); // gather os info

// if platform identifier is NT, return true
if ( osinfo->dwPlatformId == VER_PLATFORM_WIN32_NT )
return true;

return false;
}

 

[kangolian]

Answered my own question by reading the Help!You have to first specify the size in bytes of the structure you are passing to the function.
I wonder why it still worked in 98 though? Weird.


bool IsNTBased()
{

OSVERSIONINFO osinfo; // os version info structure
osinfo.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);

GetVersionEx( &osinfo ); // gather os info
cout << &quot;Platform ID = &quot; << osinfo.dwPlatformId << &quot;\n&quot;;

if ( osinfo.dwPlatformId == VER_PLATFORM_WIN32_NT )
return true;

return false;
}