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<head>
<title>hoc(1) - Plan 9 from User Space</title>
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<tr><td width=20><td><b>HOC(1)</b><td align=right><b>HOC(1)</b>
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<br>
<p><font size=+1><b>NAME </b></font><br>
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hoc – interactive floating point language<br>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<tt><font size=+1>hoc</font></tt> [ <i>file ...</i> ] [ <tt><font size=+1>−e</font></tt> <i>expression</i> ]<br>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<i>Hoc</i> interprets a simple language for floating point arithmetic,
at about the level of BASIC, with C-like syntax and functions.
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The named <i>files</i> are read and interpreted in order. If no <i>file</i>
is given or if <i>file</i> is <tt><font size=+1>−</font></tt> <i>hoc</i> interprets the standard input. The
<tt><font size=+1>−e</font></tt> option allows input to <i>hoc</i> to be specified on the command line,
to be treated as if it appeared in a file.
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<i>Hoc</i> input consists of <i>expressions</i> and <i>statements</i>. Expressions
are evaluated and their results printed. Statements, typically
assignments and function or procedure definitions, produce no
output unless they explicitly call <i>print</i>.
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Variable names have the usual syntax, including <tt><font size=+1>_</font></tt>; the name <tt><font size=+1>_</font></tt>
by itself contains the value of the last expression evaluated.
The variables <tt><font size=+1>E</font></tt>, <tt><font size=+1>PI</font></tt>, <tt><font size=+1>PHI</font></tt>, <tt><font size=+1>GAMMA</font></tt> and <tt><font size=+1>DEG</font></tt> are predefined; the last
is 59.25..., degrees per radian.
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Expressions are formed with these C-like operators, listed by
decreasing precedence.<br>
<tt><font size=+1>^</font></tt> exponentiation<br>
<tt><font size=+1>! − ++ −−<br>
* / %<br>
+ −<br>
> >= < <= == !=<br>
&&<br>
||<br>
= += −= *= /= %=<br>
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</font></tt>
Built in functions are <tt><font size=+1>abs</font></tt>, <tt><font size=+1>acos</font></tt>, <tt><font size=+1>asin</font></tt>, <tt><font size=+1>atan</font></tt> (one argument), <tt><font size=+1>cos</font></tt>,
<tt><font size=+1>cosh</font></tt>, <tt><font size=+1>exp</font></tt>, <tt><font size=+1>int</font></tt>, <tt><font size=+1>log</font></tt>, <tt><font size=+1>log10</font></tt>, <tt><font size=+1>sin</font></tt>, <tt><font size=+1>sinh</font></tt>, <tt><font size=+1>sqrt</font></tt>, <tt><font size=+1>tan</font></tt>, and <tt><font size=+1>tanh</font></tt>. The
function <tt><font size=+1>read(x)</font></tt> reads a value into the variable <tt><font size=+1>x</font></tt> and returns
0 at EOF; the statement <tt><font size=+1>print</font></tt> prints a list of expressions that
may include string constants such as
<tt><font size=+1>"hello\n"</font></tt>.
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<tt><font size=+1>
</font></tt>Control flow statements are <tt><font size=+1>if</font></tt>-<tt><font size=+1>else</font></tt>, <tt><font size=+1>while</font></tt>, and <tt><font size=+1>for</font></tt>, with braces
for grouping. Newline ends a statement. Backslash-newline is equivalent
to a space.
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Functions and procedures are introduced by the words <tt><font size=+1>func</font></tt> and
<tt><font size=+1>proc</font></tt>; <tt><font size=+1>return</font></tt> is used to return with a value from a function.<br>
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<p><font size=+1><b>EXAMPLES </b></font><br>
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<tt><font size=+1>func gcd(a, b) {<br>
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temp = abs(a) % abs(b)<br>
if(temp == 0) return abs(b)<br>
return gcd(b, temp)<br>
</table>
}<br>
for(i=1; i<12; i++) print gcd(i,12)<br>
</font></tt>
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<p><font size=+1><b>SOURCE </b></font><br>
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<tt><font size=+1>/usr/local/plan9/src/cmd/hoc<br>
</font></tt>
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<p><font size=+1><b>SEE ALSO </b></font><br>
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<a href="../man1/bc.html"><i>bc</i>(1)</a>, <a href="../man1/dc.html"><i>dc</i>(1)</a><br>
B. W. Kernighan and R. Pike, <i>The Unix Programming Environment,</i>
Prentice-Hall, 1984<br>
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<p><font size=+1><b>BUGS </b></font><br>
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Error recovery is imperfect within function and procedure definitions.<br>
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