Searching an Array with an Index

To find out which element satisfies a LOOKUP search, start the search at a particular element in the array. To do this type of search, make the entries in the calculation specifications as you would for an array without an index. However, in factor 2, enter the name of the array to be searched, followed by a parenthesized numeric field (with zero decimal positions) containing the number of the element at which the search is to start. This numeric constant or field is called the index because it points to a certain element in the array. The index is updated with the element number which satisfied the search or is set to 0 if the search failed.

You can use a numeric constant as the index to test for the existence of an element that satisfies the search starting at an element other than 1.

All other rules that apply to an array without an index apply to an array with an index.

Figure 79 shows a LOOKUP on an array with an index.

*...1....+....2....+....3....+....4....+....5....+....6....+....7...
FFilename++IPEASFRlen+LKlen+AIDevice+.Keywords++++++++++++++++++++++++++++
FARRFILE   IT   F   25            DISK
F*
DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++
DDPTNOS           S              5S 0 DIM(50) FROMFILE(ARRFILE)
DDPTDSC           S             20A   DIM(50) ALT(DPTNOS)
D*
CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq..
C* The Z-ADD operation begins the LOOKUP at the first element in DPTNOS.
C                   Z-ADD     1             X                 3 0
C* At the end of a successful LOOKUP, when an element has been found
C* that contains an entry equal to the search argument DPTNUM,
C* indicator 20 is set on and the MOVE operation places the department
C* description, corresponding to the department number, into DPTNAM.
C     DPTNUM        LOOKUP    DPTNOS(X)                              20
C* If an element is not found that is equal to the search argument,
C* element X of DPTDSC is moved to DPTNAM.
C                   IF        NOT *IN20
C                   MOVE      DPTDSC(X)     DPTNAM           20
C                   ENDIF

This example shows the same array of department numbers, DPTNOS, as Figure 78. However, an alternating array of department descriptions, DPTDSC, is also defined. Each element in DPTDSC is 20 positions in length. If there is insufficient data in the file to initialize the entire array, the remaining elements in DPTNOS are filled with zeros and the remaining elements in DPTDSC are filled with blanks.