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Handling Numeric Data
2.7 Using the Arithmetic Statements
Arithmetic expressions in nonarithmetic statements are also affected.
Nonarithmetic statements, such as the IF statement, allow arithmetic expressions
to be used, but do not provide a mechanism like the ON SIZE ERROR phrase to
detect errors in evaluation. If such an error occurs, the behavior of the statement
is unpredictable; in the case of an IF statement, result of the comparison is
undefined.
Similar considerations apply in other contexts, such as the use of arithmetic
expressions as subscript expressions or reference-modification components.
2.7.2.2 Using the /ARITHMETIC Qualifier
You can specify /ARITHMETIC=NATIVE or STANDARD (
-arithmetic native
or
standard
) on the COBOL command line to control whether native arithmetic
or standard arithmetic is used to evaluate arithmetic operations and statements.
These options have the following effects:
NATIVE Arithmetic operations will produce results that are reasonably compatible
with releases for Compaq COBOL for OpenVMS Alpha prior to Version 2.7
and also with Compaq COBOL for OpenVMS VAX.
STANDARD Most common arithmetic operations will produce results that are
predictable, reasonable, and portable. In this context, portable means
that the results will be identical from implementation to implementation.
/ARITHMETIC=STANDARD forces /MATH_INTERMEDIATE=CIT4
(described in Section 2.7.2.1).
The default is /ARITHMETIC=NATIVE (
-arithmetic native
).
Using the OPTIONS Paragraph
An alternative way to specify native or standard arithmetic is to use the
OPTIONS paragraph in the Identification Division of your Compaq COBOL
program. There you can specify ARITHMETIC IS NATIVE or STANDARD. See
the Compaq COBOL Reference Manual for the syntax and details.
2.7.3 Specifying a Truncation Qualifier
The
-trunc
flag (on Tru64 UNIX) or the /[NO]TRUNCATE qualifier (on
OpenVMS Alpha) specifies how the Compaq COBOL compiler stores values
in COMPUTATIONAL receiving items.
By default (assuming that the
-trunc
flag is turned off, or /NOTRUNCATE is
set), Compaq COBOL truncates values according to the Alpha hardware storage
unit (word, longword, or quadword) allocated to the receiving item.
If you specify
-trunc
or /TRUNCATE the compiler truncates values according to
the number of decimal digits specified by the PICTURE clause.
2.7.4 Using the ROUNDED Phrase
Rounding is an important option that you can use with arithmetic operations.
You can use the ROUNDED phrase with any Compaq COBOL arithmetic
statement. Rounding takes place only when the ROUNDED phrase requests it,
and then only if the intermediate result has low-order digits that cannot be stored
in the result.
Compaq COBOL rounds off by addinga5totheleftmost truncated digit of the
absolute value of the intermediate result before it stores that result.
2–12 Handling Numeric Data