The ON SIZE ERROR Phrase and NOT ON SIZE ERROR Phrase

If, after decimal point alignment, the absolute value of a result of an arithmetic operation exceeds the largest value that can be contained in the associated resultant-identifier, a size error condition exists. Division by zero always causes a size error condition. Note that the results of division by zero when no ON SIZE ERROR phrase is specified are unpredictable. The size error condition applies only to the final results, except in MULTIPLY and DIVIDE statements, in which case the size error condition applies to the intermediate results as well.

Violation of the rules for the evaluation of exponentiation always terminates the arithmetic operation and always causes a size error condition.

If the ROUNDED phrase is specified, rounding takes place before checking for size error. When such a size error condition occurs, the subsequent action depends on whether or not the SIZE ERROR phrase is specified, as follows:

ON SIZE ERROR Phrase Not Specified

When a size error condition occurs, the value of those resultant- identifier(s) affected is undefined. Any subsequent use of the resultant-identifier(s) affected is also unpredictable in effect. Values of resultant-identifier(s) for which no size error condition occurs are unaffected by size errors that occur for other resultant-identifier(s) during execution of this operation.

After completion of the arithmetic operation, control is transferred to the end of the arithmetic statement and the NOT ON SIZE phrase, if specified, is ignored.

Results of division by zero, when no ON SIZE ERROR is specified, are unpredictable. You can avoid this by using the CHECKDIV Compiler directive and O RTS switch.

ON SIZE ERROR Phrase Specified

When a size error condition occurs, then the values of resultant- identifier(s) affected by the size errors are not altered. Values of resultant-identifier(s) for which no size error condition occurs are unaffected by size errors that occur for other resultant-identifier(s) during execution of this operation. After completion of the execution of this operation, the imperative statement in the SIZE ERROR phrase is executed.

For the ADD statement with the CORRESPONDING phrase and the SUBTRACT statement with the CORRESPONDING phrase, if any of the individual operations produces a size error condition, the imperative statement in the ON SIZE ERROR phrase is not executed until all of the individual additions or subtractions are completed.

If a size error condition occurs, any NOT ON SIZE ERROR phrase is ignored whether or not an ON SIZE ERROR phrase is specified.

When both ON SIZE ERROR and NOT ON SIZE ERROR phrases are specified, and the statement in the phrase that is executed does not contain any explicit transfer of control, then, if necessary, an implicit transfer of control is made after execution of the phrase to the end of the arithmetic statement.