# Arithmetic Expression

Arithmetic expressions are conditions that are a combination of variables or 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-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.

Unary operatorMeaning
+ Multiplication by +1
- Multiplication by -1

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.

Binary operatorMeaningEqualent Statement
- SubtractionSUBTRACT Statement
* MultiplicationMULTIPLY Statement
/ DivisionDIVIDE Statement
** Exponentiation
(In some COBOL extensions)

Arithmetic operator's execution order -

The evaluation order of operators is -

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

Note! All unary and binary operators are only used with COMPUTE statements. The arithmetic statements can also perform similar calculations. Note that each mode of usage from the above two has its own advantages and disadvantages.

## Arithmetic Statements -

The COBOL arithmetic statements are -

## 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 -

Nondate second operandDate field second operand
Nondate first operand Nondate Date field
Date field first operand Date field Not allowed

### Results of using date fields in subtraction -

Nondate second operandDate field second operand
Nondate first operand Nondate Not allowed
Date field first operand Date field Nondate