Re: looking for an example of lookahead fields

Charles,

Suppose I have a Input Primary file that is program described and I want to

know the current record value of the field and the next record value of
the
same field, is it possible to do it with a lookahead indicator?

It isn't a real indicator, but yes, you can get the value of any fields in
the next record provided it is a program described file.  Externally
described files do not support look ahead fields.

You just have another I-spec section naming the record positions you are
interested in, and giving them unique field names.  The values from the
current record are in the fields listed under the normal I-specs, and the
values from the next record are in the field(s) listed under the **
delimited I-specs.  If the file has multiple record types, you must examine
the codes yourself. The look ahead fields get populated from the next record
without regard to the record format or type.

Look-ahead was useful in the days of mandatory Primary files (can you spell
card reader?) and you needed more control over "level breaks" or "total
time" processing than simple Lx breaks could accomodate.  Its usage is much
rarer now -- its probably been 25 years since I wrote a program using
look-ahead.

Doug