73 lines
7.3 KiB
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73 lines
7.3 KiB
HTML
<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function COUNT, COUNT-IF, COUNT-IF-NOT</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_reduce.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_sequen.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_length.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="count"><A NAME="count-if"><A NAME="count-if-not"><I>Function</I> <B>COUNT, COUNT-IF, COUNT-IF-NOT</B></A></A></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>count</B> <I>item sequence <TT>&key</TT> from-end start end key test test-not</I> => <I>n</I><P>
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<B>count-if</B> <I>predicate sequence <TT>&key</TT> from-end start end key</I> => <I>n</I><P>
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<B>count-if-not</B> <I>predicate sequence <TT>&key</TT> from-end start end key</I> => <I>n</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>item</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<I>sequence</I>---a <A REL=DEFINITION HREF="26_glo_p.htm#proper_sequence"><I>proper sequence</I></A>. <P>
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<I>predicate</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of one <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>argument</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>from-end</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. The default is <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A>. <P>
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<I>test</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>test-not</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>start</I>, <I>end</I>---<A REL=DEFINITION HREF="26_glo_b.htm#bounding_index_designator"><I>bounding index designators</I></A> of <I>sequence</I>. The defaults for <I>start</I> and <I>end</I> are <TT>0</TT> and <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, respectively. <P>
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<I>key</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of one argument, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>n</I>---a non-negative <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A> less than or equal to the <A REL=DEFINITION HREF="26_glo_l.htm#length"><I>length</I></A> of <I>sequence</I>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#count"><B>count</B></A>, <A REL=DEFINITION HREF="#count-if"><B>count-if</B></A>, and <A REL=DEFINITION HREF="#count-if-not"><B>count-if-not</B></A> count and return the number of <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>elements</I></A> in the <I>sequence</I> <A REL=DEFINITION HREF="26_glo_b.htm#bounded"><I>bounded</I></A> by <I>start</I> and <I>end</I> that <A REL=DEFINITION HREF="26_glo_s.htm#satisfy_the_test"><I>satisfy the test</I></A>. <P>
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The <I>from-end</I> has no direct effect on the result. However, if <I>from-end</I> is <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>, the <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>elements</I></A> of <I>sequence</I> will be supplied as <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> to the <I>test</I>, <I>test-not</I>, and <I>key</I> in reverse order, which may change the side-effects, if any, of those functions. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(count #\a "how many A's are there in here?") => 2
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(count-if-not #'oddp '((1) (2) (3) (4)) :key #'car) => 2
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(count-if #'upper-case-p "The Crying of Lot 49" :start 4) => 2
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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 be prepared to 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>sequence</I> is not a <A REL=DEFINITION HREF="26_glo_p.htm#proper_sequence"><I>proper sequence</I></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=CHILD HREF="17_b.htm">Section 17.2 (Rules about Test Functions)</A>, <A REL=CHILD HREF="03_f.htm">Section 3.6 (Traversal Rules and Side Effects)</A> <P>
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<P><B>Notes:</B><P>
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<P>
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The <TT>:test-not</TT> <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>argument</I></A> is deprecated. <P>
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The <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> <A REL=DEFINITION HREF="#count-if-not"><B>count-if-not</B></A> is deprecated. <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/iss345.htm">TEST-NOT-IF-NOT:FLUSH-ALL</A><LI> <A REL=CHILD HREF="../Issues/iss240.htm">MAPPING-DESTRUCTIVE-INTERACTION:EXPLICITLY-VAGUE</A><LI> <A REL=CHILD HREF="../Issues/iss284.htm">RANGE-OF-START-AND-END-PARAMETERS:INTEGER-AND-INTEGER-NIL</A><LI> <A REL=CHILD HREF="../Issues/iss332.htm">SUBSEQ-OUT-OF-BOUNDS</A><P></UL><HR>
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