TOPS-20 PASCAL Language Manual - Bitsavers

EXPRESSIONS
Table 3-1:
Arithmetic Operators
Operator
Example
Meaning
--------------------------
+ A+B
A-B
* A*B
** A**B
Add l\ and B
Subtract B from A
Multiply A by B
Ra ise A to the power of B
I
AlB
Divide A by B
DIV
A DIV B
Divide A
by B and truncate the result
MOD
A MOD B
Produce the remainder after dividing A by
B; B must be greater than 0
The addition, subtraction, muJtiplication, and exponentiation (+, ,
*, and **) operators work on both integer and real values. They
produce real results when applied to real values and integer results
when applied to integer values. If the expression contains values of
both types, the result is a real number. The only exception to these
rules concerns exponentiation. PASCAL defines the results of an
integer raised to the power of a negative integer as follows:
Base
Exponen t
Result
0 Negative or 0
1 Negative
-1 Negative and odd
-1 Negative and even
Any o the r
integer
Negative
For example, the expression 1**(-3) equals 1;
(-1)**(-4) equals 1; and 3**(-3) equals o.
Error
1
-1
1
(-1)**{-3) equals -1;
o
The division (I) operator can be used on both real and integer values,
but always produces a real result. Use of the division (I) operator
can therefore cause errors in precision in expressions involving
integers.
The DIV, MOD, and REM operators apply to integer values only.
DIV divides one integer by another, producing an integer result. DIV
truncates the result; that is, it drops any fraction. It does not
round the result. For example, the expression 23 DIV 12 equals 1, and
(-5) DIV 3 equals -1.
The MOD and REM operators return the remainder after dividing one
operand by another. Both operators can be used only with integer
values and always produce integer results.
The MOD operator can be used only when the divisor is greater than 0;
it always returns a positive result. For example, the expression 5
MOD 3 (5 modulo 3) returns a value of 2, and (-5) MOD 3 returns a
value of 1.
3-2