Common InstallShield functions and their Usage

Getting a property string

   1: NUMBER nvBufferLen;

   2: STRING svInstallDir;

   3: MsiGetProperty(hMSI, "INSTALLDIR", svInstallDir, nvBufferLen);

Where:
hMSI = handle of the MSI (gets automatically passed into functions)
INSTALLDIR = The name of the property to get
svInstallDir = The variable in which to store the returned property value
nvBufferLen = The length of the buffer, often set to 255.

---

Setting a property string 

   1: MsiSetProperty(hMSI, "INSTALLDIR", "C:\Program Files\InstallationDirectory");

Where:
hMSI = handle of the MSI (gets automatically passed into functions)
INSTALLDIR = The name of the property to set
Value = The value of the property to set to

---

Converting a number to string and vice versa

   1: number nTemp;

   2: string svTemp; 

   3: nTemp = 25;

   4:  

   5: NumToStr(svTemp, nTemp); // 25 -> "25" 

   6: StrToNum(nTemp, svTemp); // "25" -> 25

---

String comparison

   1: if (StrCompare("String A", "String B") == 0) then

   2:     // do something here

   3: endif;

---

String concatenation

   1: STRING svTemp;

   2: Sprintf(svTemp,  

   3:     "A string taking two parameters %s %s",

   4:     "Parameter 1", "Parameter 2");

---

String Trim(…) (Extracted from http://community.installshield.com/showthread.php?t=24423)

   1: function Trim(aString)   

   2:     BOOL done;    

   3:     NUMBER startIndex;   

   4:     NUMBER endIndex;    

   5:     NUMBER aByte;

   6: begin    

   7:     startIndex = 0;  

   8:     endIndex = StrLength( aString ) - 1;

   9:     done = ( startIndex > endIndex );

  10:     while ( !done )

  11:         GetByte( aByte, aString, startIndex );        

  12:         if ( aByte = ASCII_SPACE ) then

  13:             startIndex = startIndex + 1;

  14:             done = ( startIndex > endIndex );

  15:         else

  16:             done = TRUE;

  17:         endif;

  18:     endwhile;

  19:     done = ( startIndex > endIndex );

  20:  

  21:     while ( !done )

  22:         GetByte( aByte, aString, endIndex );

  23:         if ( aByte = ASCII_SPACE ) then

  24:             endIndex = endIndex - 1;

  25:             done = ( startIndex > endIndex );

  26:         else

  27:             done = TRUE;

  28:         endif;

  29:     endwhile;

  30:  

  31:     if ( startIndex > endIndex ) then

  32:         aString = "";

  33:     else

  34:         StrSub( aString, aString, startIndex, endIndex - startIndex + 1 );    

  35:     endif;

  36:     return 0;

  37: end;

---

Reading XML using MS XML DOM 6 (Inspired by http://community.installshield.com/showthread.php?t=101600&page=2)

   1: OBJECT oDoc, oNode, oNodeList;

   2: NUMBER nvBufferLen, nTemp;

   3: STRING svXPathQuery, svValue, svTemp, svMessage, svError, svLine, svLinePos;

   4:  

   5: set oDoc = CreateObject("Msxml2.DOMDocument.6.0");  

   6: if (IsObject(oDoc) = FALSE) then

   7:     MessageBox("MSXML DOM-Document Connection Failed", 0);

   8:     return -1;

   9: endif;

  10:       

  11: oDoc.async = FALSE;  

  12: oDoc.setProperty("SelectionLanguage", "XPath");

  13: oDoc.load( svInstallDir ^ UI_APP_CONFIG );

  14:  

  15: if ( oDoc.parseError.errorCode != 0 ) then

  16:     NumToStr ( svError , oDoc.parseError.errorCode );

  17:     NumToStr ( svLine , oDoc.parseError.line );

  18:     NumToStr ( svLinePos , oDoc.parseError.linepos );

  19:     MessageBox ( "The XML File did not load correctly.\n" + 

  20:                  "Error Code: " + svError + "\n" +

  21:                  "Error Line: " + svLine + "\n" + 

  22:                  "Error Line Position: " + svLinePos + "\n" +

  23:                  oDoc.parseError.reason , 0 );

  24: else 

  25:     svXPathQuery = "//XPathQuery";

  26:  

  27:     try 

  28:         set oNodeList = objDOMDOC.selectNodes( strXPathQuery );

  29:     catch

  30:         nTemp = Err.Number; 

  31:         NumToStr(svTemp, nTemp);

  32:         MessageBox("Error while selecting " + strXPathQuery + " (Error + " + svTemp + ")", 0);

  33:     endcatch;

  34:     

  35:     if (oNodeList.length == 0) then

  36:        MessageBox( "No " + strXPathQuery + " elements found.", 0 );

  37:     else 

  38:         for i = 0 to ( oNodeList.length - 1 );

  39:             set oNode = oNodeList.nextNode;

  40:             try

  41:                 svValue= oNode.text;

  42:                 //svValue = oNode.attributes.getNamedItem( strAttributeName ).value; // to get attribute value

  43:             catch

  44:                 MessageBox("No value found for " + strXPathQuery, 0);

  45:             endcatch;

  46:         endfor;

  47:     endif;

  48: endif;