MPE/iX Shell and Utilities Reference Manual, Vol 1

bc(1) MPE/iX Shell and Utilities bc(1)

displays

By default, bc displays the result of any evaluated instruction followed by a newline. bc also

saves the last value displayed in a special variable . so that you can use it in subsequent cal-

culations.

Numbers

Numbers consist of an optional minus (–) sign followed by a sequence of zero or more digits,

followed by an optional decimal point (.), followed by a sequence of zero or more digits.

Valid digits are 0 through 9, and the hexadecimal digits A through F. The uppercase letters

represent the values from 10 through 15. There must be at least one digit, either before or

after the decimal point. If not, bc interprets the decimal point as the special variable . men-

tioned earlier.

A number can be arbitrarily long and may contain spaces. Here are some valid numbers with

an input base of 10:

0 0. .0 -3.14159 +09. -12 1 000 000

Here are some valid numbers with an input base of 16 (ibase=16):

0 FF FF.3 -10.444 A1

See Bases for more information.

A ﬁnal point is that you cannot break up numbers with commas; you can write 1000000 or 1

000 000, but 1,000,000 results in an error message.

Identiﬁers

Identiﬁers are used as names for variables, functions, or arrays. Valid identiﬁers may include

sequences containing any number of letters, digits or the underscore (_) character, but must

start with a lowercase letter. Spaces are not allowed in identiﬁers. The ability to use identif-

iers more than one character in length is an extension not found in traditional implementations

of bc.

• A variable holds a single numeric value. You can declare variables as local to a function

using the auto statement (see Functions). All other variables are global and can be used

anywhere. You do not need to declare global variables. bc creates variables as it

requires them, with an initial value of zero. (Remember that there is also the special vari-

able . (dot) which contains the result of the last calculation.)

• A function is a sequence of instructions that calculates a single value. A list of zero or

more values enclosed in parentheses always follow a function name, as in

my_func(3.14159). See Functions later in this man page.

1-46 Commands and Utilities