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<html><head><title>XLISP and</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>and</h1>
<hr>
<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
<td><nobr>Type:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>special form (fsubr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xlcont.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<p><div class="box">
<dl>
<dt><nobr>(<b>and</b> [<i>expr1</i> ... ])</nobr></dt>
<dd><i>exprN</i> - an expression<br>
returns - <a href="nil.htm">NIL</a> if any expression evaluates
to <nobr><a href="nil.htm">NIL</a> ,</nobr> otherwise the value
of the last expression<br>
<b>Note:</b> evaluation of expressions stops after the first
expression that evaluates to <a href="nil.htm">NIL</a></dd>
</dl>
</div></p>
<h2>Description</h2>
<p>The 'and' special form evaluates a sequence of expressions and returns
the effect of a logical AND on the expressions. <nobr>If, at</nobr> any
point, an expression is <a href="nil.htm">NIL</a>, then
<a href="nil.htm">NIL</a> is returned as the result of the 'and'
function. <nobr>If all</nobr> of the expressions have a
<nobr>non-<a href="nil.htm">NIL</a></nobr> value, the value of the last
expression is returned as the result. Evaluation of the expressions will
stop when an expression evaluates <nobr>to <a href="nil.htm">NIL</a></nobr>,
none of the subsequent expressions will be evaluated. <nobr>If there</nobr>
are no expressions, then 'and' returns <a href="t.htm"> T </a>
as its result.</p>
<h2>Examples</h2>
<pre class="example">
(and t t t) => T</font>
(and nil t) => NIL</font>
(and t nil) => NIL</font>
(and) => T</font>
</pre>
<p>Some more practical examples:</p>
<pre class="example">
> (and T "boo" "hiss" T "rah")
"rah" <font color="#008844">; return value of AND</font>
> (and (princ "hi") NIL (princ "ho"))
hi <font color="#008844">; prints "hi"</font>
NIL <font color="#008844">; return value of AND</font>
</pre>
See <a href="princ.htm">princ</a>.
<pre class="example">
> (setq a 5 b 6) <font color="#008844">; set up A and B</font>
6 <font color="#008844">; return value of SETQ</font>
> (if (and (numberp a) <font color="#008844">; if A is a number</font>
(numberp b) <font color="#008844">; and B is a number</font>
(< a b)) <font color="#008844">; and A < B</font>
(print "A is less than B") <font color="#008844">; then do this</font>
(print "error")) <font color="#008844">; else do this</font>
"A is less than B" <font color="#008844">; screen output of PRINT</font>
"A is less than B" <font color="#008844">; return value of IF</font>
</pre>
<p>See <a href="number-lessp.htm"> < </a>,
<a href="if.htm"> if </a>, <a href="print.htm">print</a>,
<a href="setq.htm">setq</a>.</p>
<p>See also:</p>
<ul>
<li><nobr>Contents → <a href="../manual/contents.htm#control-constructs">Control Constructs</a></nobr></li>
</ul>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
<hr>
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<a href="../manual/xlisp-man-index.htm">XLISP 2.0</a> -
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