iX Computer Systems - Edition 1 (32715-90001)

3- 34

Examples

4+7*2 = 4+(7*2) = 4+14 = 18

(4+7)*2 = 11*2 = 22

3-2+1 = (3-2)+1 = 1+1 = 2

3-(2+1) = 3-3 = 0

NOT A**3 MOD 12 + 75 = B AND C OR D =

(((((NOT(A**3)) MOD 12) + 75) = B) AND C) OR D

Result Type

If an arithmetic operation has two operands of the same type, the

operation is performed using that type. The intermediate result is of

that type, and an error occurs if the intermediate result is out of the

range of the final result type. The following are exceptions:

* Short integer arithmetic, performed in integer arithmetic.

* Exponentiation in which the base is converted to a real for all

types. The exponent is converted to a real for decimal, short

decimal, and short real. The exponents for integers and short

integers are not converted. That is, a short integer remains a short

integer, and an integer remains an integer.

Examples

10 INTEGER A,B

20 REAL C

30 C=A+B

99 END

In line 30 of the above program, the intermediate result of A+B is an

integer. It is converted to a real number when it is assigned to the

real variable, C.

If an arithmetic operation has two operands of different types, one or

both operands are converted to one type before the operation. The type

that they are converted to depends on the default numeric type.

Precision can be lost when numbers are converted between real and dec-

imal types. Overflow can occur when numbers are converted to a type

with a smaller range (for example, real to short real).

Subunits

A program can be divided into program units consisting of one main

program unit followed by one or more subunits. In this section, the main

program unit is called the main program.

A subunit is a series of program lines that can be called with

parameters, by another program unit. The calling program unit transfers

control to the subunit; the subunit executes and returns control to the

calling program unit. The calling program unit can be the main program

or another subunit.