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Updated version of an article that was originally published in the November 2000 issue of the InstallShield Newsletter

How to Identify Windows 2000 and Window Me in a Setup Program

Abstract: With the release of Microsoft's latest operating system versions some developers are unsure how these can be detected and distinguished from each other. This is a problem especially if the setup authoring tool they are using is too old to have built in support for these new operating systems. This article describes how to determine whether a computer is running Windows 95 or 98, Windows Me, Windows NT 4 or Windows 2000. Instructions are given for InstallShield Professional versions 5.x and 6.x and Windows Installer.

The essential step to understand the identification of Windows types and versions is to recognize that there are only two "families" or technologies of 32 bit operating systems from Microsoft: 9x and NT. All Windows versions, including Windows 2000 and Windows Me, are members of any of these two families.

When you start a computer with Windows 2000, the splash screen already tells you that it is "based on NT technology". So without the influence of the marketing staff, Windows 2000 would probably have been called "Windows NT 5.0".

When Microsoft released Windows Me, some mockers called it "Windows 98 Third Edition" because many parts of it are identical to Windows 98. Of course there are some add-ons and even several substantial changes, but it is still a member of the Windows 9x family. This is also indicated by its version number, that has been set to 4.90.

Table 1: Windows version numbers

Operating system identification in InstallScript

Calling GetSystemInfo in any InstallShield version

InstallShield's scripting language, that is not only supported in InstallShield Professional 5.x and 6.x, but also in InstallShield for Windows Installer (version 1.1 and above), includes the GetSystemInfo function that can be used to identify the operating system family and version. You do this in two steps, as shown in code sample 1. First you call GetSystemInfo with OS in the first parameter to find out the operating system family. Then you call it with WINMAJOR (and in case of Windows 9x one more time with WINMINOR) to get the Windows version number.

Special Treatment: Identifying Windows Me with InstallShield 5

Calling the GetSystemInfo function to detect Windows Me works fine in InstallShield 6, but fails in InstallShield 5. This is because Windows Me returns 4.10 instead of 4.90 when asked for its version and therefore is identified as Windows 98.

To improve compatibility with older applications, Windows Me has a feature to "lie" about its version. Microsoft has created this function because some programs simply check the Windows version, and refuse to run if the version is higher than what the programmer expected when he created the application. Since most applications written for Windows 95 or 98 will also work on Windows Me, Windows circumvents the version test by returning 4.10 instead of 4.90 for such applications. Microsoft decided that setups created with InstallShield 5 belong to this group of programs, while it is okay to know the real Windows version for setups created with InstallShield 6.

The reasons for this operating system cloaking are questionable, but we have to live with it. This means that we must use other methods to distingush between Windows 98 and Me in InstallShield 5. Fortunately this isn't very hard: We can examine the file version of a core operating system file, e.g. Kernel32.dll. This can be done by calling the InstallShield functions VerGetFileVersion to retrieve the version, and VerCompare to see if the file version is 4.90.0.0 or above.

// InstallShield 6 requires that ifx.h be included
#if _ISCRIPT_VER >= 0x600
    #include "ifx.h"
#endif

NUMBER nvWinFamily, nvWinMajor, nvWinMinor;
STRING svResult;

program
    // Detect Windows family
    GetSystemInfo(OS, nvWinFamily, svResult);
    
    if ( nvWinFamily = IS_WINDOWSNT ) then
    
        // Check for NT 4 or Windows 2000
        GetSystemInfo(WINMAJOR, nvWinMajor, svResult);
        if ( nvWinMajor >= 5 ) then
            MessageBox("Windows 2000 or above detected", INFORMATION);
        elseif ( nvWinMajor = 4 ) then
            MessageBox("Windows NT 4 detected", INFORMATION);
        elseif ( nvWinMajor = 3 ) then
            MessageBox("Windows NT 3 detected", INFORMATION);
        else
            MessageBox("Unknown Windows NT version", INFORMATION);
        endif;
    
    elseif ( nvWinFamily = IS_WINDOWS95 ) then
    
        // Check for Windows 95, Windows 98, or Windows Me
        GetSystemInfo(WINMAJOR, nvWinMajor, svResult);
        GetSystemInfo(WINMINOR, nvWinMinor, svResult);
       
        if ( nvWinMajor = 4 ) then
            if ( nvWinMinor >= 90 ) then
                MessageBox("Windows Me or above detected", INFORMATION);
            elseif ( nvWinMinor >= 10) then
#if _ISCRIPT_VER >= 0x600
                MessageBox("Windows 98 detected", INFORMATION);
#else
                // In IS5 Windows Me lies about its version
                // so we check the file version of kernel32.dll
                VerGetFileVersion(WINSYSDIR ^ "kernel32.dll", svResult);
                if ( VerCompare(svResult, "4.90.0.0", VERSION) = LESS_THAN ) then
                    MessageBox("Windows 98 detected", INFORMATION);
                else
                    MessageBox("Windows Me or above detected", INFORMATION);
                endif;
#endif
            else
                MessageBox("Windows 95 detected", INFORMATION);
            endif;
        else
            MessageBox("Unknown Windows 9x version", INFORMATION);
        endif;
    
    else
        MessageBox("No 32 bit operating system", WARNING);
    endif;
endprogram

Code sample 1: Calling GetSystemInfo

Remarks about code sample 1:

• The header file ifx.h is required for InstallShield 6.x, but doesn't exist in InstallShield 5.x. To make the source code compatible with both versions, the built in constant _ISCRIPT_VER is used to detect the version of InstallShield. _ISCRIPT_VER is 0x600 in IS6, and undefined in IS5.
• Instead of the constant IS_WINDOWS95 we could have used IS_WINDOWS9X, they are identical. However IS_WINDOWS9X was introduced with IS 5.5. To make the script also compatible with IS 5.0 and 5.1, the older constant IS_WINDOWS95 was used here.
• The Kernel32.dll file version check is only used in InstalShield 5. GetSystemInfo correctly returns 4.90 for Windows Me in InstallShield 6.

Using the SYSINFO structure in InstallShield Professional 6.x and Windows Installer

In InstallShield Professional 6.x (and InstallShield for Windows Installer 1.1 and above, which uses the same scripting engine) you don't need to call the GetSystemInfo function - InstallShield does this for you behind the scenes during initialisation, and stores the results in the SYSINFO structure. Since this structure already has a member to identify Windows 2000, less code is required (see figure 2)

#include "ifx.h" 
NUMBER nvWinFamily, nvWinMajor, nvWinMinor; 
STRING svResult; 

program 
    if ( SYSINFO.WINNT.bWin2000 ) then 
        MessageBox("Windows 2000 detected", INFORMATION); 
    elseif ( SYSINFO.WINNT.bWinNT4 ) then 
        MessageBox("Windows NT 4 detected", INFORMATION); 
    elseif ( SYSINFO.WINNT.bWinNT351 ) then 
        MessageBox("Windows NT 3 detected", INFORMATION); 
    elseif ( SYSINFO.WINNT.bWinNT ) then 
        MessageBox("Unknown Windows NT version", INFORMATION); 
    elseif ( SYSINFO.WIN9X.bWin98 ) then 
        MessageBox("Windows 98 detected", INFORMATION); 
    elseif ( SYSINFO.WIN9X.bWin95 ) then 
        MessageBox("Windows 95 detected", INFORMATION); 
    elseif ( SYSINFO.WIN9X.bWin9X ) then 
        MessageBox("Windows Me or above detected", INFORMATION); 
    else MessageBox("No 32 bit operating system", WARNING); 
    endif;
endprogram

Code sample 2: Using the SYSINFO structure

Remarks about code sample 2:

• In this sample, any Windows 9x family operating system that is not 95 or 98 is interpreted as "Windows Me or above". We could have used SYSINFO.nWinMajor and SYSINFO.nWinMinor for further examinations in this case.
• InstallShield Professional - Standard Edition version 6.22 and InstallShield Professional - Windows Installer Edition version 2.0 introduce a new structure member SYSINFO.WIN9X.bWinMe that can be used to detect Windows Me.

Operating system identification in Windows Installer

In InstallShield Professional - Windows Installer Edition you don't have to write custom code to identify the operating system. The Windows Installer engine provides two built in properties for this purpose: Version9X and VersionNT. The following table shows their values:

Table 2: Operating system properties in Windows Installer

Notes:

• The property names Version9X and VersionNT are case sensitive.
• Windows Installer is not available on Windows NT 3.5.

Here are some examples of conditions based on operating system:

About the Author

Stefan Krueger is working as freelance setup consultant. Besides his contract work, he answers questions in various newsgroups and maintains the InstallSite.org web site, a place where setup developers share resources and information among peers.

If you have any comments about this article, or want to suggest a topic that Stefan should discuss in a future article, please write to . To read Stefan's articles from previous issues of the InstallShield Newsletter, please visit http://www.installsite.org/isnews.htm.

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