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GPERF(1)			      FSF			      GPERF(1)

NAME
       gperf - generate	a perfect hash function	from a key set

SYNOPSIS
       gperf [OPTION]... [INPUT-FILE]

DESCRIPTION
       GNU `gperf' generates perfect hash functions.

       If  a  long option shows	an argument as mandatory, then it is mandatory
       for the equivalent short	option also.

   Input file interpretation:
       -e, --delimiters=DELIMITER-LIST
	      Allow user to provide a string  containing  delimiters  used  to
	      separate keywords	from their attributes.	Default	is ",\n".

       -t, --struct-type
	      Allows  the  user	 to  include a structured type declaration for
	      generated	code. Any text before %% is  considered	 part  of  the
	      type  declaration.  Key  words  and additional fields may	follow
	      this, one	group of fields	per line.

   Language for	the output code:
       -L, --language=LANGUAGE-NAME
	      Generates	code in	the specified language.	Languages handled  are
	      currently	C++, ANSI-C, C,	and KR-C. The default is C.

   Details in the output code:
       -K, --slot-name=NAME
	      Select name of the keyword component in the keyword structure.

       -F, --initializer-suffix=INITIALIZERS
	      Initializers for additional components in	the keyword structure.

       -H, --hash-fn-name=NAME
	      Specify name of generated	hash function. Default is `hash'.

       -N, --lookup-fn-name=NAME
	      Specify name of  generated  lookup  function.  Default  name  is
	      `in_word_set'.

       -Z, --class-name=NAME
	      Specify  name  of	 generated  C++	 class.	 Default name is `Per-
	      fect_Hash'.

       -7, --seven-bit
	      Assume 7-bit characters.

       -c, --compare-strncmp
	      Generate comparison code using strncmp rather than strcmp.

       -C, --readonly-tables
	      Make the contents	of generated  lookup  tables  constant,	 i.e.,
	      readonly.

       -E, --enum
	      Define  constant	values using an	enum local to the lookup func-
	      tion rather than with defines.

       -I, --includes
	      Include the necessary system  include  file  <string.h>  at  the
	      beginning	of the code.

       -G, --global
	      Generate	the  static table of keywords as a static global vari-
	      able, rather than	hiding it inside of the	lookup function	(which
	      is the default behavior).

       -W, --word-array-name=NAME
	      Specify name of word list	array. Default name is `wordlist'.

       -S, --switch=COUNT
	      Causes  the  generated  C	code to	use a switch statement scheme,
	      rather than an array lookup table.  This can lead	to a reduction
	      in both time and space requirements for some keyfiles. The COUNT
	      argument determines how many switch statements are generated.  A
	      value  of	 1  generates  1 switch	containing all the elements, a
	      value of 2 generates 2 tables with 1/2 the elements in each  ta-
	      ble,  etc.  If COUNT is very large, say 1000000, the generated C
	      code does	a binary search.

       -T, --omit-struct-type
	      Prevents the transfer of the  type  declaration  to  the	output
	      file.  Use this option if	the type is already defined elsewhere.

   Algorithm employed by gperf:
       -k, --key-positions=KEYS
	      Select the key positions used in the hash	function.  The	allow-
	      able  choices range between 1-126, inclusive.  The positions are
	      separated	by commas, ranges may be used, and key	positions  may
	      occur  in	 any  order.   Also, the meta-character	'*' causes the
	      generated	hash function to consider ALL  key  positions,	and  $
	      indicates	 the ``final character'' of a key, e.g., $,1,2,4,6-10.

       -l, --compare-strlen
	      Compare key lengths before  trying  a  string  comparison.  This
	      helps  cut  down on the number of	string comparisons made	during
	      the lookup.

       -D, --duplicates
	      Handle keywords that hash	to duplicate values.  This  is	useful
	      for certain highly redundant keyword sets.

       -f, --fast=ITERATIONS
	      Generate	the  gen-perf.hash  function  ``fast''.	This decreases
	      gperf's running time at the cost of minimizing  generated	 table
	      size.  The  numeric  argument  represents	the number of times to
	      iterate when resolving a collision. `0' means ``iterate  by  the
	      number of	keywords''.

       -i, --initial-asso=N
	      Provide an initial value for the associate values	array. Default
	      is 0. Setting this value larger helps inflate the	 size  of  the
	      final table.

       -j, --jump=JUMP-VALUE
	      Affects the ``jump value'', i.e.,	how far	to advance the associ-
	      ated character value upon	collisions. Must  be  an  odd  number,
	      default is 5.

       -n, --no-strlen
	      Do not include the length	of the keyword when computing the hash
	      function.

       -o, --occurrence-sort
	      Reorders input keys by frequency of occurrence of	the key	 sets.
	      This should decrease the search time dramatically.

       -r, --random
	      Utilizes randomness to initialize	the associated values table.

       -s, --size-multiple=N
	      Affects  the size	of the generated hash table. The numeric argu-
	      ment N indicates ``how many times	larger or smaller'' the	 asso-
	      ciated  value  range should be, in relationship to the number of
	      keys, e.g. a value of 3 means  ``allow  the  maximum  associated
	      value  to	 be  about  3  times  larger  than the number of input
	      keys.'' Conversely, a value of -3	means ``make the maximum asso-
	      ciated  value  about  3  times  smaller than the number of input
	      keys. A larger table should decrease the time  required  for  an
	      unsuccessful  search,  at	 the  expense  of  extra  table	space.
	      Default value is 1.

   Informative output:
       -h, --help
	      Print this message.

       -v, --version
	      Print the	gperf version number.

       -d, --debug
	      Enables the debugging option (produces  verbose  output  to  the
	      standard error).

REPORTING BUGS
       Report bugs to <bug-gnu-utils@gnu.org>.

SEE ALSO
       The full	documentation for gperf	is maintained as a Texinfo manual.  If
       the info	and gperf programs are properly	installed at  your  site,  the
       command

	      info gperf

       should give you access to the complete manual.

GNU gperf 2.7.2			September 2000			      GPERF(1)

NAME | SYNOPSIS | DESCRIPTION | REPORTING BUGS | SEE ALSO

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