ItemDifferenceList (Stringlist function)

Compare Stringlist to delimited Stringlist

This method determines which items in a Stringlist do not appear as an entry in a separator-delimited item in a second Stringlist, and it places them on an output Stringlist. In some sense, the output Stringlist is the "difference" between a Stringlist and a separator-delimited Stringlist item.

ItemDifferenceList is a member of the Stringlist class.

ItemDifferenceList Syntax

%outlist = %sl:ItemDifferenceList(sl1, itemnum, [separator])

Syntax Terms

%outlist

This Stringlist contains the items from %sl that do not appear in the specified item in sl1.

%sl

A Stringlist object.

sl1

The identifier of a Stringlist that contains the item that contains a delimiter-separated string that is to be scanned for each item from the method Stringlist, %sl.

itemnum

The number of the item from %sl1 that contains a delimiter-separated string that is to be scanned for each item from %sl. Each %sl item that does not appear in the delimiter-separated string becomes an item in the resultant Stringlist, %outlist.

separator

The delimiter character or characters to be used in the scanning of the indicated Stringlist item. This optional argument defaults to comma (.,), and it cannot be the null string. Specifying separator as a null string is the same as not specifying the argument or as specifying it as a comma.

Usage Notes

• All errors in ItemDifferenceList result in request cancellation.

Examples

1. As an example of the use of this method, suppose Stringlist %list1 contained these six items:

   BBB
   CC
   DDDD
   AAA
   E
   FFF
   

   Suppose Stringlist %list2 contained two items:

   X,Y,Z,
   AAA,DDDD,FFF,
   

   If this is the ItemDifferenceList invocation:

   %list3 = %list1:itemDifferenceList(%list2, 2)
   

   The resulting %list3 has three items:

   BBB
   CC
   E
   

2. If a value occurs multiple times in the first object Stringlist, it will appear the same number of times in the output Stringlist or not at all, depending on whether it appears in the separator-delimited item in the first argument Stringlist. For example, if Stringlist %list1 contained these eight items:

   TCP/IP
   SNA
   CORBA
   MQSERIES
   SNA
   TCP/IP
   IPX
   TCP/IP
   

   And if Stringlist %list2 contained these three items:

   Y2K**SECURITY**PRODUCTIVITY**METRICS**
   IND$FILE**LU6.2**SNA**MQSERIES**LU2**
   GIF**JPEG**WAV**PDF**HTML**
   

   And if this is the ItemDifferenceList invocation:

   %list3 = %list1:itemDifferenceList(%list2, '++')
   

   The resulting Stringlist %list3 has five items:

   TCP/IP
   CORBA
   TCP/IP
   IPX
   TCP/IP