81c9b0506c
* contrib/*
* Deleted 'www.' from harbour-project.org website name.
(www.harbour-project.org -> harbour-project.org)
258 lines
9.3 KiB
C
258 lines
9.3 KiB
C
/*
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* $Id$
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*/
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/*
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* Harbour Project source code:
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* STRDIFF() CT3 string function
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*
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* Copyright 2002 IntTec GmbH, Neunlindenstr 32, 79106 Freiburg, Germany
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* Author: Martin Vogel <vogel@inttec.de>
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*
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* www - http://harbour-project.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
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*
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* As a special exception, the Harbour Project gives permission for
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* additional uses of the text contained in its release of Harbour.
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*
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* The exception is that, if you link the Harbour libraries with other
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* files to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the Harbour library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by the Harbour
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* Project under the name Harbour. If you copy code from other
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* Harbour Project or Free Software Foundation releases into a copy of
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* Harbour, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from them.
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*
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* If you write modifications of your own for Harbour, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice.
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*
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*/
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#include "ct.h"
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#include <limits.h>
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/* $DOC$
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* $FUNCNAME$
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* STRDIFF()
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* $CATEGORY$
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* CT3 string functions
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* $ONELINER$
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* Evaluate the "Edit (Levensthein) Distance" of two strings
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* $SYNTAX$
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* STRDIFF (<cString1>, <cString2>, [<nReplacementPenalty>], [<nDeletionPenalty>],
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* [<nInsertionPenalty>]) -> <nDistance>
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* $ARGUMENTS$
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* <cString1> string at the "starting point" of the transformation process, default is ""
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* <cString2> string at the "end point" of the transformation process, default is ""
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* <nReplacementPenalty> penalty points for a replacement of one character, default is 3
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* <nDeletionPenalty> penalty points for a deletion of one character, default is 6
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* <nInsertionPenalty> penalty points for an insertion of one character, default is 1
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* $RETURNS$
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* <nDistance> penalty point sum of all operations needed to transform <cString1> to <cString2>
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* $DESCRIPTION$
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* The STRDIFF() functions calculates the so called "Edit" or "Levensthein" distance of two strings.
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* This distance is a measure for the number of single character replace/insert/delete operations (so called
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* "point mutations") required to transform <cString1> into <cString2> and its value will be the smallest sum of
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* the penalty points of the required operations.
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*
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* Be aware that this function is both quite time - O(len(cString1)*len(cString2)) - and memory consuming -
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* O((len(cString1)+1)*(len(cString2)+1)*sizeof(int)) - so keep the strings as short as possible.
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* E.g., on common 32 bit systems (sizeof(int) == 4), calling strdiff() with two strings of 1024 bytes
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* in length will consume 4 MB of memory. To not impose unneeded restrictions, the function will only check if
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* (len(cString1)+1)*(len(cString2)+1)*sizeof(int) <= UINT_MAX, although allocing UINT_MAX bytes will not
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* work on most systems. If this simple check fails, -1 is returned.
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*
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* Also, be aware that there can be an overflow when the penalty points are summed up: Assuming that the
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* number of transformation operations is in the order of max(len(cString1),len(cString2)), the penalty point
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* sum, that is internally stored in an "int" variable, is in the order of
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* (max(len(cString1),len(cString2))*max(nReplacementPenalty,nDeletionPenalty,nInsertionPentaly).
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* The STRDIFF() does not do an overflow check due to time performance reasons. Future versions of STRDIFF()
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* could use a type different to "int" to store the penalty point sum to save memory or to avoid overflows.
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*
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* The function is aware of the settings done by SETATLIKE(), that means that the wildchar character
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* is considered equal to ALL characters.
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*
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* $EXAMPLES$
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* ? strdiff("ABC", "ADC") // 3, one character replaced
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* ? strdiff("ABC", "AEC") // 3, dito
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* ? strdiff("CBA", "ABC") // 6, two characters replaced
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* ? strdiff("ABC", "AXBC") // 1, one character inserted
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* ? strdiff("AXBC", "ABC") // 6, one character removed
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* ? strdiff("AXBC", "ADC") // 9, one character removed and one replaced
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* $TESTS$
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* strdiff("ABC", "ADC") == 3
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* strdiff("ABC", "AEC") == 3
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* strdiff("CBA", "ABC") == 6
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* strdiff("ABC", "AXBC") == 1
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* strdiff("AXBC", "ABC") == 6
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* strdiff("AXBC", "ADC") == 9
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* $STATUS$
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* Ready
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* $COMPLIANCE$
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* STRDIFF() is compatible with CT3's STRDIFF().
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* $PLATFORMS$
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* All
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* $FILES$
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* Source is strdiff.c, library is libct.
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* $SEEALSO$
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* SETATLIKE()
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* $END$
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*/
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#define MATRIXELEMENT(__row,__col) *(piPenalty+((__row)*(sStrLen2+1))+(__col))
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static int min3( int a, int b, int c )
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{
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if( a < b )
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return ( a < c ? a : c );
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return ( b < c ? b : c );
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}
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HB_FUNC( STRDIFF )
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{
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/* param check */
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if( HB_ISCHAR( 1 ) || HB_ISCHAR( 2 ) )
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{
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/* get parameters */
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const char *pcStr1, *pcStr2;
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HB_SIZE sStrLen1, sStrLen2;
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int iReplace, iDelete, iInsert;
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int iAtLike = ct_getatlike();
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char cAtLike = ct_getatlikechar();
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int *piPenalty;
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HB_SIZE sRowCnt, sColCnt;
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if( HB_ISCHAR( 1 ) )
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{
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pcStr1 = hb_parc( 1 );
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sStrLen1 = hb_parclen( 1 );
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}
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else
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{
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pcStr1 = "";
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sStrLen1 = 0;
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}
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if( HB_ISCHAR( 2 ) )
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{
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pcStr2 = hb_parc( 2 );
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sStrLen2 = hb_parclen( 2 );
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}
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else
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{
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pcStr2 = "";
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sStrLen2 = 0;
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}
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/* check for memory consumption */
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if( ( ( double ) sStrLen1 + 1.0 ) *
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( ( double ) sStrLen2 + 1.0 ) *
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( ( double ) sizeof( int ) ) >= ( double ) UINT_MAX )
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{
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int iArgErrorMode = ct_getargerrormode();
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if( iArgErrorMode != CT_ARGERR_IGNORE )
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{
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ct_error( ( HB_USHORT ) iArgErrorMode, EG_ARG, CT_ERROR_STRDIFF, NULL,
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HB_ERR_FUNCNAME, 0, EF_CANDEFAULT, HB_ERR_ARGS_BASEPARAMS );
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}
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hb_retni( -1 );
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return;
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}
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/* get penalty points */
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if( HB_ISNUM( 3 ) )
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iReplace = hb_parni( 3 );
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else
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iReplace = 3;
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if( HB_ISNUM( 4 ) )
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iDelete = hb_parni( 4 );
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else
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iDelete = 6;
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if( HB_ISNUM( 5 ) )
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iInsert = hb_parni( 5 );
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else
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iInsert = 1;
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piPenalty = ( int * ) hb_xgrab( ( sStrLen1 + 1 ) *
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( sStrLen2 + 1 ) * sizeof( int ) );
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MATRIXELEMENT( 0, 0 ) = 0;
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for( sColCnt = 0; sColCnt <= sStrLen2 - 1; sColCnt++ )
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{
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MATRIXELEMENT( 0, sColCnt + 1 ) = MATRIXELEMENT( 0, sColCnt ) + iInsert;
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}
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for( sRowCnt = 0; sRowCnt <= sStrLen1 - 1; sRowCnt++ )
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{
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MATRIXELEMENT( sRowCnt + 1, 0 ) = MATRIXELEMENT( sRowCnt, 0 ) + iDelete;
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for( sColCnt = 0; sColCnt <= sStrLen2 - 1; sColCnt++ )
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{
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int iReplaceCost;
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if( pcStr1[sRowCnt] == pcStr2[sColCnt] ||
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( iAtLike == CT_SETATLIKE_WILDCARD &&
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( pcStr1[sRowCnt] == cAtLike ||
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pcStr2[sColCnt] == cAtLike ) ) )
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iReplaceCost = 0;
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else
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iReplaceCost = iReplace;
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MATRIXELEMENT( sRowCnt + 1, sColCnt + 1 ) =
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min3( MATRIXELEMENT( sRowCnt, sColCnt ) + iReplaceCost,
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MATRIXELEMENT( sRowCnt, sColCnt + 1 ) + iDelete,
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MATRIXELEMENT( sRowCnt + 1, sColCnt ) + iInsert );
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}
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}
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hb_retni( MATRIXELEMENT( sStrLen1, sStrLen2 ) );
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hb_xfree( piPenalty );
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}
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else /* HB_ISCHAR( 1 ) || HB_ISCHAR( 2 ) */
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{
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PHB_ITEM pSubst = NULL;
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int iArgErrorMode = ct_getargerrormode();
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if( iArgErrorMode != CT_ARGERR_IGNORE )
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{
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pSubst = ct_error_subst( ( HB_USHORT ) iArgErrorMode, EG_ARG,
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CT_ERROR_STRDIFF, NULL, HB_ERR_FUNCNAME, 0,
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EF_CANSUBSTITUTE, HB_ERR_ARGS_BASEPARAMS );
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}
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if( pSubst != NULL )
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hb_itemReturnRelease( pSubst );
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else
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hb_retni( 0 );
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}
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}
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