Compare (Stringlist function)

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Compare two Stringlists and produce Stringlist describing differences (Stringlist class)

This method compares two Stringlists and produces a Stringlist describing the differences between the two.

The Compare method object, that is, the Stringlist against which Compare is being run, must have 8-byte long sequence numbers at the start of each item. As the term "sequence numbers" suggests, these numbers must consist exclusively of numeric characters with no leading blanks, and the numbers must be in ascending, sequential order. That is, the sequence number in each Stringlist item must be greater than the sequence number in the preceding item.


[%outList =] sl:Compare( inList, [syncCount], [pad])

Syntax terms

%outList A Stringlist to contain the result of the comparison of the method input (sl) and inList Stringlists.
sl A Stringlist object. The first 8 characters of each item must be an 8-digit increasing integer; these are used as sequence numbers for the %outList items. The comparison is made using the sl items following the sequence numbers.
inList The input Stringlist, which contains data that does not include 8-byte sequence numbers. This is a required argument.
syncCount A number indicating a synchronization count. When sl, the method Stringlist, and the inList Stringlist are being compared and a difference is found, syncCount indicates the number of lines that must match before they are treated as a true match. This is an optional argument, and it defaults to 1.
pad The pad character to be used to pad any input item during the comparison to items in the other input Stringlist. This is an optional argument, and it defaults to blank.

Usage notes

  • All errors in Compare result in request cancellation.
  • The output Stringlist produced by Compare is in a format that is suitable as input to Update.


For example, assume the Stringlist object, identified by %objList, contains these items:

00010000b 00020000 00030000print 'Quentin Compson' 00040000 00050000end

And the input argument Stringlist, identified by %argList, contains these items:

b print 'Quentin Compson' print 'Harvard Diving Team, 1908' end

This statement compares the two Stringlists:

%outList = %objList:compare(%argList)

The result is the Stringlist, identified by %outList, which contains:

.li;./ I 00030000 $ 00030001 00010000 print 'Harvard Diving Team, 1908'

The method Stringlist for Compare (%objlist, above) can be most easily created with AppendOpenProcedure, using the third parameter, seqIncrement, to indicate a sequence number.

See also