NAME

dc - desk calculator


SYNOPSIS

dc [files ...]


DESCRIPTION

DC evaluates integer expressions from the source files,
one expression per input line.
If no input files are given, or the filename '-' is specified,
dc reads from the standard input.

Ordinarily dc operates on decimal integer arithmetic expressions,
but the user may specify an input base and output base other
than decimal.

Expressions may be simple arithmetic expressions or
replacement expressions.
The values of simple expressions are
written on standard output when they are evaluated.
Replacement expressions are used to hold temporary values, and are
not automatically printed.

A simple expression is a normal arithmetic expression using
numbers, variables, parentheses, and the following
operators, listed in order of precedence:


+  -          unary plus and negation operators.  These may
                          only appear at the start of a simple
                          expression or after a "("

**            exponentiation

*   /   %     multiply, divide, modulo (remainder)

+   -         add, subtract

== !=         relations - equals, not equal to,
>  >=         greater than, greater than or equal to,
<  <=         less than, less than or equal to
                       (!=, ^=, ~= all treated as "not equal")

!             unary logical not (also ~ and ^)

|   &         logical or, and



The logical operators ! | & and the relational operators result in
the values 1 for true and 0 for false.

A replacement expression is:


name = simple expression

where 'name' is a character string of (virtually) any length,
starting with a letter and consisting of only letters and digits.
(The characters a-f should not be considered letters when operating
in hexadecimal mode.)
Variables are automatically declared when they first appear to
the left of an "=" sign,
and they should not be used in a simple expression until they have
been declared.

Radix Control


Radix control is available in 2 ways:

1) There are default radix values for both input and output which
may be changed by setting the predefined variables 'ibase'
(input base) and 'obase' (output base).  (Radix 10 is always
used to evaluate and/or print radix-defining expressions.)
For example,


ibase = 2

obase = 16


would accept input in binary and print results in hexadecimal.

2)  The radix of individual numbers may be explicitly given by
following the number with an underscore character and then the
desired radix.
For example,


100_16

would specify the hex number 100 (256 in decimal).



EXAMPLES




10 + (-64 / 2**4)

would print the answer "6"



temp = 101_2
temp == 5


would print the answer "1" (true)



ibase = 16
obase = 2
1a + f


would print the answer "101001"



ibase = 16
numa = 100_10
numb = 100
numa + numb


would print the answer "356"



FILES

None



SEE ALSO

macro, the UNIX M4 macro package

The UNIX tools dc and bc



DIAGNOSTICS



arith evaluation stack overflow

arithmetic expressions have been nested too deeply.
The size of the stack is set by the MAXSTACK definition
in the source code.


number error

an input number has a number/character bigger than the current
radix



expression error

invalid arithmetic expression



AUTHOR

Philip H. Scherrer (Stanford U.)


BUGS/DEFICIENCIES

Dc only works with integers

The maximum value allowed depends on the host machine and is the
largest Fortran integer