6.2.32.7 "COBOL Language Reference" IBM Library Server

6.2.32.7 Binary Search

The Format 2 SEARCH ALL statement executes a binary search. The search index need not be initialized by SET statements, because its setting is varied during the search operation so that its value is at no time less than the value of the first table element, nor ever greater than the value of the last table element. The index used is always that associated with the first index-name specified in the OCCURS clause.

The results of a SEARCH ALL operation are predictable only when:

The data in the table is ordered in ASCENDING/DESCENDING KEY order
The contents of the ASCENDING/DESCENDING keys specified in the WHEN clause provide a unique table reference.

identifier-1

Identifier-1 can be:

A data item subordinate to a data item that contains an OCCURS clause; that is, it can be a part of a 2- to 7-dimensional table. In this case, the data description entry must specify an INDEXED BY phrase for each dimension of the table.
X A DBCS item if the ASCENDING/DESCENDING KEY is defined as a DBCS
X item.

Identifier-1 cannot be:

USAGE IS INDEX
X A floating-point data item
X A data item defined with USAGE IS POINTER, USAGE IS
X PROCEDURE-POINTER, or USAGE IS OBJECT REFERENCE
X A windowed date field

Identifier-1 must refer to all occurrences within the table element; that is, it must not be subscripted or reference-modified.

The Data Division description of identifier-1 must contain an OCCURS clause with the INDEXED BY option. It must also contain the KEY IS phrase in its OCCURS clause.

AT END

The condition that exists when the search operation terminates without satisfying the condition specified in any of the associated WHEN phrases.

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6.2.32.7 Binary Search

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