Arithmetic Expressions

An arithmetic expression is a user-defined formula that performs arithmetic calculations. These are combinations of variables and numbers separated by arithmetic operators.

Arithmetic expressions may contain any of the following –

• Variables declared as numeric.
• Numeric values.
• Arithmetic operators.
• An arithmetic expression is enclosed in parentheses.

For example,

 WORKING-STORAGE SECTION.
 01 WS-VAR.
    05 WS-INPUT      PIC 9(03) VALUE 20.
    05 WS-OUTPUT     PIC 9(03).

 PROCEDURE DIVISION.
	 COMPUTE WS-OUTPUT = WS-INPUT + 10.

In the above example, WS-OUTPUT = WS-INPUT + 10 is the arithmetic expression.

Rules to Remember -

• All variables or values should be of type numeric.
• SPACE should separate each parameter in the expression (variables, operators, etc.).

Let us discuss about COBOL arithmetic operators to understand the arithmetic expression in detail.

Arithmetic Operators -

All arithmetic operators are majorly divided into two types and those are –

1. Unary Operators
2. Binary Operators

Unary Operators -

Unary operators are arithmetic operators that perform an action on a single operand. There are two unary operators, negative ( - ) and positive ( + ). The negative unary operator reverses the sign of an expression from positive to negative or negative to positive.

Binary Operators -

A binary operation is an operation that requires two inputs. These inputs are known as operands in mathematical terminology. The binary operations are - addition, multiplication, subtraction, and division.

Arithmetic operator's execution order -

The evaluation order of operators is -

• Expressions within parentheses → ( ).
• Unary operator → +, -.
• Exponentiation → **
• Multiplication and division → *, /.
• Binary addition and subtraction → +, -.

Arithmetic Statements -

The COBOL arithmetic statements are -

• ADD Statement
• SUBTRACT Statement
• MULTIPLY Statement
• DIVIDE Statement
• COMPUTE Statement

Arithmetic with date fields -

Arithmetic operations on a date field are restricted to -

• Adding days to a date field.
• Subtracting days from a date field.
• Subtracting a date field from a compatible date field.

The following operations are not allowed -

• Any operation between incompatible dates.
• Adding two date fields if they are not compatible.
• Subtracting a date field from a nondate.
• Unary minus, division, exponentiation, or multiplication of or by a date field.

Results of using date fields in addition -

Results of using date fields in subtraction -