z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

c
Arithmetic Operations
bc provides a large number of arithmetic operations. Following standard arithmetic
conventions, some operations are calculated before others. For example,
multiplications take place before additions unless you use parentheses to group
operations. Operations that take place first are said to have a higher precedence
than operations that take place later.
Operations also have an associativity. The associativity dictates the order of
evaluation when you have a sequence of operations with equal precedence. Some
operations are evaluated left to right, whereas others are evaluated right to left. The
following list shows the operators of bc from highest precedence to lowest.
bc Operator Associativity
( ) Left to right
Unary ++ −− Not applicable
Unary − ! Not applicable
^ Right to left
* / % Left to right
+ − Left to right
= ^= *= /= %= +=
Right to left
== = != < >
None
&& Left to right
|| Left to right
bc’s order of precedence is not the same as C’s. In C, the assignment operators
have the lowest precedence.
The following list describes what each operation does. In the descriptions, A and B
can be numbers, variables, array elements, or other expressions. V must be either a
variable or an array element.
(A) Indicates that this expression—A—should be evaluated before any other
operations are performed on it.
-A Is the negation of the expression.
!A Is the logical complement of the expression. If A evaluates to zero, !A
evaluates to 1. If A is not zero, !A evaluates to zero. This operator is unique
to this version of bc.
++V Adds 1 to the value of V. The result of the expression is the new value of V.
− −V Subtracts 1 from the value of V. The result of the expression is the new
value of V.
V++ Adds 1 to the value of V, but the result of the expression is the old value of
V.
V− − Subtracts 1 from the value of V, but the result of the expression is the old
value of V.
A ^ B Calculates A to the power B. B must be an integer. The scale of the result of
A^B is:
54 z/OS V1R9.0 UNIX System Services Command Reference