Provided by: gperf_3.1-1_amd64 bug


       gperf - generate a perfect hash function from a key set


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


       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.

   Output file location:
       --output-file=FILE Write output to specified file.

       The results are written to standard output if no output file is specified or if it is -.

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

       -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.

              Consider  upper  and  lower  case  ASCII characters as equivalent. Note that locale
              dependent case mappings are ignored.

   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 ANSI-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-function-name=NAME
              Specify name of generated hash function. Default is 'hash'.

       -N, --lookup-function-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 'Perfect_Hash'.

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

       -l, --compare-lengths
              Compare  key  lengths  before  trying a string comparison. This is necessary if the
              keywords contain NUL bytes. It  also  helps  cut  down  on  the  number  of  string
              comparisons made during the lookup.

       -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 function rather than with

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

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

       -P, --pic
              Optimize  the  generated table for inclusion in shared libraries.  This reduces the
              startup time of programs using a shared library containing the generated code.

       -Q, --string-pool-name=NAME
              Specify  name  of  string  pool  generated  by  option  --pic.   Default  name   is

              Use NULL strings instead of empty strings for empty keyword table entries.

              Specify prefix for the constants like TOTAL_KEYWORDS.

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

              Specify name of length table array. Default name is 'lengthtable'.

       -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 table, 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 allowable choices range
              between 1-255, 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.

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

       -m, --multiple-iterations=ITERATIONS
              Perform multiple choices of the -i and -j values, and choose the best results. This
              increases the running time by a factor of ITERATIONS but does a good job minimizing
              the generated table size.

       -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 associated 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.

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

       -s, --size-multiple=N
              Affects the size of the generated hash table. The numeric argument N indicates "how
              many times larger or smaller" the associated 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
              1/3 means "make the maximum associated 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).


       Written by Douglas C. Schmidt and Bruno Haible.


       Report bugs to <>.


       Copyright © 1989-2017 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or
       later <>
       This  is free software: you are free to change and redistribute it.  There is NO WARRANTY,
       to the extent permitted by law.


       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.