HOC(1)HOC(1)
NAME
hoc – interactive floating point language
SYNOPSIS
hoc
[
-e
expression
]
[
file ...
]
DESCRIPTION
Hoc
interprets a simple language for floating point arithmetic,
at about the level of BASIC, with C-like syntax and
functions.
The named
files
are read and interpreted in order.
If no
file
is given or if
file
is
-
hoc
interprets the standard input.
The
-e
option allows input to
hoc
to be specified on the command line, to be treated as if it appeared in a file.
Hoc
input consists of
expressions
and
statements.
Expressions are evaluated and their results printed.
Statements, typically assignments and function or procedure
definitions, produce no output unless they explicitly call
print.
Variable names have the usual syntax, including
_;
the name
_
by itself contains the value of the last expression evaluated.
The variables
E,
PI,
PHI,
GAMMA
and
DEG
are predefined; the last is 59.25..., degrees per radian.
Expressions are formed with these C-like operators, listed by
decreasing precedence.
^
exponentiation
! - ++ --
* / %
+ -
> >= < <= == !=
&&
||
= += -= *= /= %=
Built in functions are
abs,
acos,
asin,
atan
(one argument),
cos,
cosh,
exp,
int,
log,
log10,
sin,
sinh,
sqrt,
tan,
and
tanh.
The function
read(x)
reads a value into the variable
x
and returns 0 at EOF;
the statement
print
prints a list of expressions that may include
string constants such as
\fL"hello\n".
Control flow statements are
if-else,
while,
and
for,
with braces for grouping.
Newline ends a statement.
Backslash-newline is equivalent to a space.
Functions and procedures are introduced by the words
func
and
proc;
return
is used to return with a value from a function.
EXAMPLES
func gcd(a, b) {
temp = abs(a) % abs(b)
if(temp == 0) return abs(b)
return gcd(b, temp)
}
for(i=1; i<12; i++) print gcd(i,12)
SOURCE
/sys/src/cmd/hoc
SEE ALSO
bc(1),
dc(1)
B. W. Kernighan and R. Pike,
The Unix Programming Environment,
Prentice-Hall, 1984
BUGS
Error recovery is imperfect within function and procedure definitions.