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Posted onApril 15, 2013

Right Here


Posted onApril 15, 2013


Posted onApril 8, 2013

As most of those who have built “F” codes know, there are three levels in the stack. Sometimes a forth level is needed. This is particularly true when using the string extract code “[]”. A “feature” of code processing is that value-marks can be used to separate command statements.
Suppose that you need to examine the last character in a string for a numeric value. If it’s numeric then report that value, else report nothing. Attribute 5 is tested in the following example.


001 S
002 0
003 NBR
008 F;5;(L0)}F;5;LPV;”1”;[];(P(1N))
009 R
010 3

The character “}” following the “(L0)” string is a value mark. The “LPV” returns the result of the prior command. The “[]” extract function expects to find the string in Stack 3, the start position in Stack 2 and the length in Stack 1. “Wishing for a Stack 4” is due to the length of the string function needed to “load” Stack 1. If the length of string function (L0) was included in a single value command sequence, then it would have “pushed” a needed data value off the stack – “into Stack 4”. Therefore a multi-value sequence was needed.

Of interest – the commands separated by value-marks can be any valid correlative or conversion code. In other words, you can combine “F” codes with “A” codes with… you get the idea.

Using the above example – suppose that the results needed to be concatenated to the end of the data value in attribute 6.
Then attribute 8 in the dictionary item is:
008 F;5;(L0)}F;5;LPV;”1”;[];(P(1N))}A;6:(LPV)
The character “}” preceding the “A” is a second value mark.