glenda.party
term% ls -F
term% pwd
$home/manuals/9front/1/hoc
term% cat index.txt
HOC(1)                      General Commands Manual                     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 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.

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, Pren‐
       tice-Hall, 1984

BUGS
       Error recovery is imperfect within function and procedure definitions.



                                                                        HOC(1)