xstr(1)                                                             xstr(1)




 NAME    [Toc]    [Back]
      xstr - extract strings from C programs to implement shared strings

 SYNOPSIS    [Toc]    [Back]
      xstr [-c] [-] [file]

 DESCRIPTION    [Toc]    [Back]
      xstr maintains a file strings into which strings in component parts of
      a large program are hashed.  These strings are replaced with
      references to this common area.  This serves to implement shared
      constant strings, which are most useful if they are also read-only.

      The command:

           xstr -c name

      extracts the strings from the C source in name, replacing string
      references with expressions of the form (&xstr[number]) for some
      number.  An appropriate declaration of xstr is placed at the beginning
      of the file.  The resulting C text is placed in the file x.c, for
      subsequent compiling.  The strings from this file are placed in the
      strings database if they are not there already.  Repeated strings and
      strings that are suffixes of existing strings do not cause changes to
      the data base.

      After all components of a large program have been compiled, a file
      xs.c declaring the common xstr space, can be created by the command:

           xstr

      This xs.c file should then be compiled and loaded with the rest of the
      program.  If possible, the array can be made read-only (shared),
      saving space and swap overhead.

      xstr can also be used on a single file.  A command:

           xstr name

      creates files x.c and xs.c as before, without using or affecting any
      strings file in the same directory.

      It may be useful to run xstr after the C preprocessor if any macro
      definitions yield strings or if there is conditional code containing
      strings that are not, in fact, needed.  xstr reads from its standard
      input when the argument - is given.  An appropriate command sequence
      for running xstr after the C preprocessor is:

           cc -E name.c | xstr -c -
           cc -c x.c
           mv x.o name.o




 Hewlett-Packard Company            - 1 -   HP-UX 11i Version 2: August 2003






 xstr(1)                                                             xstr(1)




      xstr does not touch the file strings unless new items are added, thus
      make can avoid remaking xs.o unless truly necessary (see make(1)).

 WARNINGS    [Toc]    [Back]
      If a string is a suffix of another string in the data base, but the
      shorter string is seen first by xstr, both strings are placed in the
      data base, when placing only the longer one there would be sufficient.

 AUTHOR    [Toc]    [Back]
      xstr was developed by the University of California, Berkeley.

 FILES    [Toc]    [Back]
      strings        Data base of strings
      x.c            Massaged C source
      xs.c           C source for definition of array xstr
      /tmp/xs*       Temp file when `xstr name' does not touch strings

 SEE ALSO    [Toc]    [Back]
      mkstr(1).


 Hewlett-Packard Company            - 2 -   HP-UX 11i Version 2: August 2003