74 lines
4.1 KiB
HTML
74 lines
4.1 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 HASH-TABLE-COUNT</TITLE>
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<A NAME="hash-table-count"><I>Function</I> <B>HASH-TABLE-COUNT</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>hash-table-count</B> <I>hash-table</I> => <I>count</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>hash-table</I>---a <A REL=DEFINITION HREF="26_glo_h.htm#hash_table"><I>hash table</I></A>. <P>
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<I>count</I>---a non-negative <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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Returns the number of entries in the <I>hash-table</I>. If <I>hash-table</I> has just been created or newly cleared (see <A REL=DEFINITION HREF="f_clrhas.htm#clrhash"><B>clrhash</B></A>) the entry count is <TT>0</TT>. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(setq table (make-hash-table)) => #<HASH-TABLE EQL 0/120 32115135>
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(hash-table-count table) => 0
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(setf (gethash 57 table) "fifty-seven") => "fifty-seven"
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(hash-table-count table) => 1
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(dotimes (i 100) (setf (gethash i table) i)) => NIL
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(hash-table-count table) => 100
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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><P>
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<P>
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<A REL=DEFINITION HREF="f_clrhas.htm#clrhash"><B>clrhash</B></A>, <A REL=DEFINITION HREF="f_remhas.htm#remhash"><B>remhash</B></A>, <A REL=DEFINITION HREF="m_setf_.htm#setf"><B>setf</B></A> of <A REL=DEFINITION HREF="f_gethas.htm#gethash"><B>gethash</B></A> <P>
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<P><B>Exceptional Situations:</B> None.
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<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_hash_4.htm#hash-table-size"><B>hash-table-size</B></A> <P>
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<P><B>Notes:</B><P>
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<P>
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The following relationships are functionally correct, although in practice using <A REL=DEFINITION HREF="#hash-table-count"><B>hash-table-count</B></A> is probably much faster: <P>
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<PRE>
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(hash-table-count table) ==
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(loop for value being the hash-values of table count t) ==
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(let ((total 0))
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(maphash #'(lambda (key value)
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(declare (ignore key value))
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(incf total))
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table)
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total)
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</PRE>
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