68 lines
4.5 KiB
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68 lines
4.5 KiB
HTML
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<TITLE>CLHS: Function NTHCDR</TITLE>
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<A NAME="nthcdr"><I>Function</I> <B>NTHCDR</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>nthcdr</B> <I>n list</I> => <I>tail</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>n</I>---a non-negative <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A>. <P>
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<I>list</I>---a <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A>, which might be a <A REL=DEFINITION HREF="26_glo_d.htm#dotted_list"><I>dotted list</I></A> or a <A REL=DEFINITION HREF="26_glo_c.htm#circular_list"><I>circular list</I></A>. <P>
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<I>tail</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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Returns the <A REL=DEFINITION HREF="26_glo_t.htm#tail"><I>tail</I></A> of <I>list</I> that would be obtained by calling <A REL=DEFINITION HREF="f_car_c.htm#cdr"><B>cdr</B></A> <I>n</I> times in succession. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(nthcdr 0 '()) => NIL
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(nthcdr 3 '()) => NIL
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(nthcdr 0 '(a b c)) => (A B C)
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(nthcdr 2 '(a b c)) => (C)
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(nthcdr 4 '(a b c)) => ()
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(nthcdr 1 '(0 . 1)) => 1
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(locally (declare (optimize (safety 3)))
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(nthcdr 3 '(0 . 1)))
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Error: Attempted to take CDR of 1.
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B> None.
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<P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B><P>
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<P>
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Should signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_tp_err.htm#type-error"><B>type-error</B></A> if <I>n</I> is not a non-negative <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A>. <P>
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For <I>n</I> being an integer greater than <TT>1</TT>, the error checking done by <TT>(nthcdr </TT><I>n</I><TT> </TT><I>list</I><TT>)</TT> is the same as for <TT>(nthcdr (- </TT><I>n</I><TT> 1) (cdr </TT><I>list</I><TT>))</TT>; see the <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> <A REL=DEFINITION HREF="f_car_c.htm#cdr"><B>cdr</B></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_car_c.htm#cdr"><B>cdr</B></A>, <A REL=DEFINITION HREF="f_nth.htm#nth"><B>nth</B></A>, <A REL=DEFINITION HREF="f_rest.htm#rest"><B>rest</B></A> <P>
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<P><B>Notes:</B> None.
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<P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss138.htm">DOTTED-LIST-ARGUMENTS:CLARIFY</A><LI> <A REL=CHILD HREF="../Issues/iss013.htm">ARGUMENTS-UNDERSPECIFIED:SPECIFY</A><P></UL><HR>
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