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<TITLE>Judy(3X)</TITLE>
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<TABLE border=0 width="100%"><TR>
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<TD width="40%" align="left">Judy(3X)</TD>
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<TD width="10%" align="center"> </TD>
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<TD width="40%" align="right">Judy(3X)</TD>
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C libraries for creating and accessing dynamic arrays
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<DT><B>SYNOPSIS</B></DT>
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<A href="Judy1_3x.htm">Judy1</A> - maps an Index (word) to a bit
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<A href="JudyL_3x.htm">JudyL</A> - maps an Index (word) to a word
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<A href="JudySL_3x.htm">JudySL</A> - maps an Index (string) to a word
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<DT><B>DESCRIPTION</B></DT>
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The Judy family of functions supports fully dynamic arrays.
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These arrays may be indexed by a 32- or 64-bit word (depending on the
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processor) or a string.
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A dynamic array that is sparsely populated can be thought of as a
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There are 3 different Judy mappings currently supported:
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<BR>Judy1 maps an Index (word) to a bit.
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<BR>JudyL maps an Index (word) to a word.
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<BR>JudySL maps an Index (string) to a word.
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<A href="Judy1_3x.htm">Judy1 functions</A>
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<A href="JudyL_3x.htm">JudyL functions</A>,
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<B>Index</B> should be declared as a <B>Word_t</B> type.
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<B>Word_t</B> is defined in the
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<B>Judy.h</B> header file as a
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32- or 64-bit unsigned native integer, and has
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the same number of bits as a pointer.
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<A href="JudySL_3x.htm">JudySL functions</A>, each index is a
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null-terminated string.
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Judy arrays are both <B>speed-</B> and <B>memory-efficient</B>,
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with no tuning or configuration required, across a
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wide range of index set types (sequential, periodic,
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Judy's speed and memory usage are typically better than other data storage
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models such as skiplists,
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binary trees, b-trees, or even hashing, and improves with very large data sets.
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A Judy array is created merely by defining a null pointer
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and then storing (inserting) the first element into the array under that
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The memory used by a Judy array is proportional to the population
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Judy has two Application Program Interfaces (APIs): a C macro interface,
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and a function call interface.
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Because the macro forms are faster and have a simpler error handling
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interface than the equivalent functions, they are the preferred way of
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calling the Judy functions.
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Since an initial (empty) Judy array is represented by a null pointer,
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it is possible to construct an array of Judy arrays.
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In other words, a Judy array's values (except Judy1) can be pointers
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<DT><B>AUTHOR</B></DT>
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Judy was invented by Doug Baskins and implemented by Hewlett-Packard.
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(Note: Judy is named for the inventor's sister.)
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<B>FILES</B></A></DT>
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Locations of interest include:
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<DT>/usr/share/doc/Judy/</DT>
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<DD>Documents, including HTML versions of the manual entries.</DD>
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<DT>/usr/share/doc/Judy/demo/</DT>
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<DD>Demonstration program source files.</DD>
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<DT><B>SEE ALSO</B></DT>
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<A href="Judy1_3x.htm">Judy1(3X)</A>,
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<A href="JudyL_3x.htm">JudyL(3X)</A>,
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<A href="JudySL_3x.htm">JudySL(3X)</A>,
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<A href="http://www.sourcejudy.com/">
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http://www.sourcejudy.com/</A>,
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for more information and Application Notes.
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