term% cat index.txt HOC(1) General Commands Manual HOC(1)
NAME
hoc - interactive floating point language
SYNOPSIS
hoc [ 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.
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 con‐
tains 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 decreas‐
ing 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 "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; re‐
turn is used to return with a value from a function. Within a function
or procedure, arguments are referred to as $1, $2, etc.; all other
variables are global.
EXAMPLES
func gcd() {
temp = abs($1) % abs($2)
if(temp == 0) return abs($2)
return gcd($2, 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, Pren‐
tice-Hall, 1984
BUGS
Error recovery is imperfect within function and procedure definitions.
HOC(1)