Finding Illustrator install path

Question

I want to create an setup app for user to install AI plugin.
For Windows and MAC, how do I find the Illustrator's installation path?
If there are more than one AI versions stalled what then?
I use Microsoft Visual Studio and XCode
Please help

Answer 1

Update to my testing of the example I gave previously.
In summary, the CoCreateInstance immediately open the latest AI version installed on the machine;  which is not desirabled, you can get AI path with aiPath = result.bstrVal and not with result.pdispVal.
This is not a good solution for finding AI folders, a good solution must be passive, your solution is active because it invokes AI itself inorder to execute its methods, the same is true for executing VBScript you proposed earlier.
complete example is here, just load and run, uncomment the #define EXEL to run excel otherwise AI will be in.
// XIcpp.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <ole2.h> // OLE2 Definitions
The AutoWrap() function simplifies most of the low-level details involved with using IDispatch directly.
Feel free to use it in your own implementations.
One caveat is that if you pass multiple parameters,
they need to be passed in reverse-order. For example:
    VARIANT parm[3];
    parm[0].vt = VT_I4; parm[0].lVal = 1;
    parm[1].vt = VT_I4; parm[1].lVal = 2;
    parm[2].vt = VT_I4; parm[2].lVal = 3;
    AutoWrap(DISPATCH_METHOD, NULL, pDisp, L"call", 3, parm[2], parm[1], parm[0]);
// AutoWrap() - Automation helper function...
HRESULT AutoWrap(int autoType, VARIANT *pvResult, IDispatch *pDisp, LPOLESTR ptName, int cArgs...) {
    // Begin variable-argument list...
    va_list marker;
    va_start(marker, cArgs);
    if(!pDisp) {
        MessageBox(NULL, L"NULL IDispatch passed to AutoWrap()", L"Error", 0x10010);
        _exit(0);
    // Variables used...
    DISPPARAMS dp = { NULL, NULL, 0, 0 };
    DISPID dispidNamed = DISPID_PROPERTYPUT;
    DISPID dispID;
    HRESULT hr;
    char buf[200];
    char szName[200];
    // Convert down to ANSI
    WideCharToMultiByte(CP_ACP, 0, ptName, -1, szName, 256, NULL, NULL);
    // Get DISPID for name passed...
    hr = pDisp->GetIDsOfNames(IID_NULL, &ptName, 1, LOCALE_USER_DEFAULT, &dispID);
    if(FAILED(hr)) {
        sprintf(buf, "IDispatch::GetIDsOfNames(\"%s\") failed w/err 0x%08lx", szName, hr);
        MessageBox(NULL, (LPCWSTR)buf, L"AutoWrap()", 0x10010);
        _exit(0);
        return hr;
    // Allocate memory for arguments...
    VARIANT *pArgs = new VARIANT[cArgs+1];
    // Extract arguments...
    for(int i=0; i<cArgs; i++) {
        pArgs[i] = va_arg(marker, VARIANT);
    // Build DISPPARAMS
    dp.cArgs = cArgs;
    dp.rgvarg = pArgs;
    // Handle special-case for property-puts!
    if(autoType & DISPATCH_PROPERTYPUT) {
        dp.cNamedArgs = 1;
        dp.rgdispidNamedArgs = &dispidNamed;
    // Make the call!
    hr = pDisp->Invoke(dispID, IID_NULL, LOCALE_SYSTEM_DEFAULT, autoType, &dp, pvResult, NULL, NULL);
    if(FAILED(hr)) {
        sprintf(buf, "IDispatch::Invoke(\"%s\"=%08lx) failed w/err 0x%08lx", szName, dispID, hr);
        MessageBox(NULL, (LPCWSTR)buf, L"AutoWrap()", 0x10010);
        _exit(0);
        return hr;
    // End variable-argument section...
    va_end(marker);
    delete [] pArgs;
    return hr;
//#define EXEL //if not defined Illustrator object is created
int _tmain(int argc, _TCHAR* argv[])
// Initialize COM for this thread...
   CoInitialize(NULL);
   // Get CLSID for our server...
   CLSID clsid;
#ifdef EXEL
   HRESULT hr = CLSIDFromProgID(L"Excel.Application", &clsid);
#else
    BSTR aiPath;
   HRESULT hr = CLSIDFromProgID(L"Illustrator.Application", &clsid);
#endif
   if(FAILED(hr)) {
      ::MessageBox(NULL, L"CLSIDFromProgID() failed", L"Error", 0x10010);
      return -1;
   // Start server and get IDispatch...
   IDispatch *pXlApp;
   //next line opens Illustrator, that is not good!!!
   hr = CoCreateInstance(clsid, NULL, CLSCTX_LOCAL_SERVER, IID_IDispatch, (void **)&pXlApp);
   if(FAILED(hr)) {
      ::MessageBox(NULL, L"Excel not registered properly", L"Error", 0x10010);
      return -2;
   // Make it visible (i.e. app.visible = 1)
#ifdef EXEL
      VARIANT x;
      x.vt = VT_I4;
      //x.lVal = 1;//show exel
      x.lVal = 0;//hide exel
      AutoWrap(DISPATCH_PROPERTYPUT, NULL, pXlApp, L"Visible", 1, x);
#endif
   // Get Workbooks collection
   IDispatch *pXlBooks;
      VARIANT result;
      VariantInit(&result);
#ifdef EXEL
      AutoWrap(DISPATCH_PROPERTYGET, &result, pXlApp, L"Workbooks", 0);
      pXlBooks = result.pdispVal;
#else
      AutoWrap(DISPATCH_PROPERTYGET, &result, pXlApp, L"path", 0);
      pXlBooks = result.pdispVal;
      aiPath = result.bstrVal;
#endif
#ifdef EXEL
   // Call Workbooks.Add() to get a new workbook...
   IDispatch *pXlBook;
      VARIANT result;
      VariantInit(&result);
      AutoWrap(DISPATCH_PROPERTYGET, &result, pXlBooks, L"Add", 0);
      pXlBook = result.pdispVal;
   // Create a 15x15 safearray of variants...
   VARIANT arr;
   arr.vt = VT_ARRAY | VT_VARIANT;
      SAFEARRAYBOUND sab[2];
      sab[0].lLbound = 1; sab[0].cElements = 15;
      sab[1].lLbound = 1; sab[1].cElements = 15;
      arr.parray = SafeArrayCreate(VT_VARIANT, 2, sab);
   // Fill safearray with some values...
   for(int i=1; i<=15; i++) {
      for(int j=1; j<=15; j++) {
         // Create entry value for (i,j)
         VARIANT tmp;
         tmp.vt = VT_I4;
         tmp.lVal = i*j;
         // Add to safearray...
         long indices[] = {i,j};
         SafeArrayPutElement(arr.parray, indices, (void *)&tmp);
   // Get ActiveSheet object
   IDispatch *pXlSheet;
      VARIANT result;
      VariantInit(&result);
      AutoWrap(DISPATCH_PROPERTYGET, &result, pXlApp, L"ActiveSheet", 0);
      pXlSheet = result.pdispVal;
   // Get Range object for the Range A1:O15...
   IDispatch *pXlRange;
      VARIANT parm;
      parm.vt = VT_BSTR;
      parm.bstrVal = ::SysAllocString(L"A1:O15");
      VARIANT result;
      VariantInit(&result);
      AutoWrap(DISPATCH_PROPERTYGET, &result, pXlSheet, L"Range", 1, parm);
      VariantClear(&parm);
      pXlRange = result.pdispVal;
   // Set range with our safearray...
   AutoWrap(DISPATCH_PROPERTYPUT, NULL, pXlRange, L"Value", 1, arr);
   // Wait for user...
   ::MessageBox(NULL, L"All done.", L"Notice", 0x10000);
   // Set .Saved property of workbook to TRUE so we aren't prompted
   // to save when we tell Excel to quit...
      VARIANT x;
      x.vt = VT_I4;
      x.lVal = 1;
      AutoWrap(DISPATCH_PROPERTYPUT, NULL, pXlBook, L"Saved", 1, x);
   // Tell Excel to quit (i.e. App.Quit)
   AutoWrap(DISPATCH_METHOD, NULL, pXlApp, L"Quit", 0);
   // Release references...
   pXlRange->Release();
   pXlSheet->Release();
   pXlBook->Release();
   pXlBooks->Release();
   pXlApp->Release();
   VariantClear(&arr);
#else
   // Wait for user...
   ::MessageBox(NULL, L"All done.", L"Notice", 0x10000);
   AutoWrap(DISPATCH_METHOD, NULL, pXlApp, L"Quit", 0);
   pXlBooks->Release();
   pXlApp->Release();
#endif
   // Uninitialize COM for this thread...
   CoUninitialize();
    return 0;