6.1.6.10 "COBOL Language Reference" IBM Library Server

6.1.6.10 Combined Conditions

Two or more conditions can be logically connected to form a combined condition.


    ___ Format _____________________________________________________________ 
   |                                                                        |
   |                  <______________________                               |
   | >>__condition-1____ _AND_ __condition-2_|___________________________>< |
   |                    |_OR__|                                             |
   |                                                                        |
   |________________________________________________________________________|

The condition to be combined can be any of the following:

A simple-condition
A negated simple-condition
A combined condition
A negated combined condition (that is, the NOT logical operator followed by a combined condition enclosed in parentheses)
Combinations of the preceding conditions that are specified according to the rules in the following table.

Combined condition element	Left most	When not leftmost, can be immediately preceded by:	Right most	When not rightmost, can be immediately followed by:

Table 28. Combined Conditions--Permissible Element Sequences
simple- condition	Yes	OR NOT AND (	Yes	OR AND )
OR AND	No	simple-condition )	No	simple-condition NOT (
NOT	Yes	OR AND (	No	simple-condition (
(	Yes	OR NOT AND (	No	simple-condition NOT (
)	No	simple-condition )	Yes	OR AND )

Parentheses are never needed when either ANDs or ORs (but not both) are used exclusively in one combined condition. However, parentheses can be needed to modify the implicit precedence rules to maintain the correct logical relation of operators and operands.

There must be a one-to-one correspondence between left and right parentheses, with each left parenthesis to the left of its corresponding right parenthesis.

Table 29illustrates the relationships between logical operators and conditions C1 and C2.

Value for C1	Value for C2	C1 AND C2	C1 OR C2	NOT (C2 AND C2)	NOT C1 AND C2	NOT (C1 OR C2)	NOT C1 OR C2

Table 29. Logical Operators and Evaluation Results of Combined Conditions
True	True	True	True	False	False	False	True
False	True	False	True	True	True	False	True
True	False	False	True	True	False	False	False
False	False	False	False	True	False	True	True

Subtopics:

Adobe, the Adobe logo, Acrobat, the Acrobat logo, and Acrobat Reader are registered trademarks of Adobe Systems incorporated.

6.1.6.10 Combined Conditions

IBM Library Server Copyright 1989, 2005 IBM Corporation. All rights reserved.