Interactively perform arbitraryprecision arithmetic or convert numbers
from one base to another. Input can be taken from
files
or read from the standard input. To exit, type
quit
or
EOF
.

c

Do not invoke
dc
; compile only.
(Since
bc
is a preprocessor for
dc
,
bc
normally invokes
dc
.)

l

Make available functions from the math library.
bc
is a language (and compiler) whose syntax resembles that of C.
bc
consists of identifiers, keywords, and symbols, which
are briefly described below. Examples follow at end.
An identifier is a single character, consisting of the lowercase
letters az.
Identifiers are used as names for variables, arrays, and functions.
Within the same program you may name a variable, an array,
and a function using the same letter. The following identifiers would
not conflict:

x

Variable
x
.

x[
i
]

Element
i
of array
x
.
i
can range from 0 to 2047
and can also be an expression.

x(y,z)

Call function
x
with parameters
y
and
z
.
ibase
,
obase
, and
scale
store a value.
Typing them on a line by themselves
displays their current value. More commonly, you would change
their values through assignment. Letters AF are treated
as digits whose values are 1015.

ibase =
n

Numbers that are input (e.g., typed) are read as base
n
(default is 10).

obase =
n

Numbers displayed are in base
n
(default is 10).
Note: Once
ibase
has been changed from 10, use digit "A"
to restore
ibase
or
obase
to decimal.

scale =
n

Display computations using
n
decimal places (default is 0,
meaning that results are truncated to integers).
scale
is normally used only for base10 computations.
A semicolon or a newline separates one statement from another.
Curly braces are needed only when grouping multiple statements.

if (
relexpr
) {
statements
}

Do one or more
statements
if relational expression
relexpr
is true; for example:
if(x==y) i = i + 1
.

while (
relexpr
) {
statements
}

Repeat one or more
statements
while
relexpr
is true; for
example:
while(i>0) {p = p*n; q = a/b; i = i1}

for (
expr1
;
relexpr
;
expr2
) {
statements
}

Similar to
while
; for example, to print the first 10 multiples of
5, you could type:
for(i=1; i<=10; i++) i*5

break

Terminate a
while
or
for
statement.

define
j
(
k
) {

Begin the definition of function
j
having a single argument
k
.
Additional arguments are allowed, separated by commas.
Statements follow on successive lines. End with a }.

auto
x
,
y

Set up
x
and
y
as variables local to a function definition,
initialized to 0 and meaningless outside the function. Must appear first.

return(
expr
)

Pass the value of expression
expr
back to the program.
Return 0 if
(
expr
)
is left off. Used in function definitions.

sqrt(
expr
)

Compute the square root of expression
expr
.

length(
expr
)

Compute how many digits are in
expr
.

scale(
expr
)

Same, but count only digits to the right of the decimal point.
These are available when
bc
is invoked with
l
.
Library functions set
scale
to 20.

s(
angle
)

Compute the sine of
angle
, a constant or expression
in radians.

c(
angle
)

Compute the cosine of
angle
, a constant or expression
in radians.

a(
n
)

Compute the arctangent of
n
, returning an angle in radians.

e(
expr
)

Compute
e
to the power of
expr
.

l(
expr
)

Compute natural log of
expr
.

j(
n
,
x
)

Compute Bessel function of integer order
n
.
These consist of operators and other symbols.
Operators can be arithmetic, unary, assignment, or relational.

arithmetic

+

*
/ % ^

unary


++ 

assignment

=+ =

=* =/ =% =^ =

relational

< <= > >= == !=

/* */

Enclose comments.

( )

Control the evaluation of expressions (change precedence).
Can also be used around assignment statements to force the
result to print.

{ }

Used to group statements.

[ ]

Array index.

"
text
"

Use as a statement to print
text
.
Note below that when you type some quantity (a number or expression),
it is evaluated and printed, but assignment statements produce no display.
ibase = 8
Octal input
.
20
Evaluate this octal number
.
16
Terminal displays decimal value
.
obase = 2
Display output in base 2 instead of base 10
.
20
Octal input
.
10000
Terminal now displays binary value
.
ibase = A
Restore base 10 input
.
scale = 3
Truncate results to 3 places
.
8/7
Evaluate a division
.
1.001001000
Oops! Forgot to reset output base to 10
.
obase=10
Input is decimal now, so "A" isn't needed
.
8/7
1.142
Terminal displays result (truncated)
.
The following lines show the use of functions:
define p(r,n){
Function p uses two arguments
.
auto v
v is a local variable
.
v = r^n
r raised to the n power
.
return(v)}
Value returned
.
scale=5
x=p(2.5,2)
x = 2.5 ^ 2
x
Print value of x
.
6.25
length(x)
Number of digits
.
3
scale(x)
Number of places right of decimal point
.
2