File r37/lisp/csl/html/r37_0118.html artifact b343702dc4 part of check-in 58a25bf8df

<A NAME=NOT>

<TITLE>NOT</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>NOT</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
<P>
 
The <em>not</em> operator returns 
<A HREF=r37_0122.html>true</A> if its argument evaluates to 

<A HREF=r37_0014.html>nil</A>, and <em>nil</em> if its argument is <em>true</em>
. 
 <P> <H3> 
syntax: </H3>
<P>
<P>
<em>not</em>(&lt;logical expression&gt;) 
<P>
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>
if not numberp(a) then write &quot;indeterminate&quot; else write a;
			 


  indeterminate; 


a := 10; 

  A := 10 


if not numberp(a) then write &quot;indeterminate&quot; else write a;
			 


  10 


if not(numberp(a) and a &lt; 0) then write &quot;positive number&quot;;
			 


  positive number

</TT></PRE><P>Logical operators can only be used in conditional statements such 
as 
<P>
<P>
<em>if</em>...<em>then</em>...<em>else</em> or <em>while</em>...<em>do</em>. 
<P>
<P>
<P>