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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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