
<A NAME=AND>

<TITLE>AND</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>AND</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
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The <em>and</em> binary logical operator returns true if both of its 
arguments are true. 
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 <P> <H3> 
syntax: </H3>
&lt;logical\_expression&gt; <em>and</em> &lt;logical\_expression&gt; 
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&lt;logical\_expression&gt; must evaluate to true or nil. 
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examples: </H3>
<P><PRE><TT>
a := 12; 

  A := 12 


if numberp a and a &lt; 15 then write a**2 else write &quot;no&quot;;
 


  144 


clear a; 

if numberp a and a &lt; 15 then write a**2 else write &quot;no&quot;;
 


  no

</TT></PRE><P>Logical operators can only be used inside conditional statements, 
such as 

<A HREF=r37_0228.html>while</A>...<em>do</em> or 

<A HREF=r37_0052.html>if</A>...<em>then</em>...<em>else</em>. <em>and</em> exami
nes each of 
its arguments in order, and quits, returning nil, on finding an 
argument that is not true. An error results if it is used in other 
contexts. 
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<em>and</em>is left associative: <em>x and y and z</em> is equivalent to 
<em>(x and y) and z</em>. 
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