6.1.6.10.1 "COBOL Language Reference" IBM Library Server

6.1.6.10.1 Order of Evaluation of Conditions

Parentheses, both explicit and implicit, define the level of inclusiveness within a complex condition. Two or more conditions connected by only the logical operators AND or OR at the same level of inclusiveness establish a hierarchical level within a complex condition. An entire complex condition, therefore, is a nested structure of hierarchical levels with the entire complex condition being the most inclusive hierarchical level.

Within this context, the evaluation of the conditions within an entire complex condition begins at the left of the condition. The constituent connected conditions within a hierarchical level are evaluated in order from left to right, and evaluation of that hierarchical level terminates as soon as a truth value for it is determined, regardless of whether all the constituent connected conditions within that hierarchical level have been evaluated.

Values are established for arithmetic expressions and functions if and when the conditions containing them are evaluated. Similarly, negated conditions are evaluated if and when it is necessary to evaluate the complex condition that they represent. For example:

NOT A IS GREATER THAN B OR A + B IS EQUAL TO C AND D IS POSITIVE

is evaluated as if parenthesized as follows:


     (NOT (A IS GREATER THAN B)) OR
     (((A + B) IS EQUAL TO C) AND (D IS POSITIVE))

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6.1.6.10.1 Order of Evaluation of Conditions

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