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Implement Phonetic ("Sounds-like") Name Searches with Double Metaphone Part I: Introduction & C++ Implementation

, 19 Mar 2007
Introduces the Double Metaphone algorithm for phonetic comparison of proper names, and provides a practical C++ implementation for use in the reader's projects.
dmetaphone_demo.zip
CSWordLookup
App.ico
bin
Release
CSWordLookup.exe
Metaphone.NET.dll
obj
Release
temp
VBScriptWordLookup
VBWordDBLookup
frmMain.frm
MSSCCPRJ.SCC
VBWordDBLookup.vbp
VBWordDBLookup.vbw
VBWordLookup.exe
VBWordLookup
frmMain.frm
MSSCCPRJ.SCC
VBWordLookup.exe
VBWordLookup.vbp
VBWordLookup.vbw
WordLookupSample
Release
WordLookupSample.exe
ASPWordDBLookup
namelist.mdb
dmetaphone_demo1.zip
App.ico
namelist.mdb
VBScriptWordLookup.vbs.fascistemailclient
frmMain.frm
MSSCCPRJ.SCC
VBWordDBLookup.vbp
VBWordDBLookup.vbw
frmMain.frm
MSSCCPRJ.SCC
VBWordLookup.vbp
VBWordLookup.vbw
dmetaphone_src.zip
MetaphoneCOM
Debug
MetaphoneCOM.aps
MetaphoneCOM.bakvpj
MetaphoneCOM.rgs
MetaphoneCOM.vpj
MetaphoneCOMps.def
MetaphoneCOMPS.vpj
Release
MetaphoneCOM.dll
MetaphoneCOM.exp
MetaphoneCOM.lib
MetaphoneCOM.res
MetaphoneLib
Debug
MetaphoneLib.bakvpj
MetaphoneLib.vpj
Release
DoubleMetaphone.obj
MetaphoneLib.lib
stdafx.obj
XPMetaphone
Debug
Release
XPMetaphone.dll
XPMetaphone.exp
XPMetaphone.lib
XPMetaphone.obj
XPMetaphone.res
XPMetaphone.aps
XPMetaphone.bakvpj
XPMetaphone.vpj
Metaphone.NET
bin
Debug
Release
Metaphone.NET.dll
Metaphone.NET.bakvpj
Metaphone.NET.csproj.user
Metaphone.NET.vpj
obj
Debug
temp
TempPE
Release
temp
TempPE
dmetaphone_src1.zip
Metaphone.NET.bakvpj
Metaphone.NET.csproj.user
Metaphone.NET.vpj
MetaphoneCOM.aps
MetaphoneCOM.bakvpj
MetaphoneCOM.rgs
MetaphoneCOM.vpj
MetaphoneCOMps.def
MetaphoneCOMPS.vpj
Test.vbs.braindeademailclient
MetaphoneLib.bakvpj
MetaphoneLib.vpj
XPMetaphone.bakvpj
XPMetaphone.vpj
/**
 * proc.cpp
 * 
 * Implementation of the SQL Server Extended stored procedure, xp_metaphone.
 * Provides SQL Server queries, stored procedures, triggers, etc, access to the
 * Double Metaphone phonetic matching algorithm.
 * 
 * For the latest version, implemenatations for other languages, and links to articles
 * I've written on how to use this and all my other Double Metaphone implementations, go to
 * http://www.nullpointer.net/anelson/
 * 
 * Implementation by Adam J. Nelson (anelson@nullpointer.net)
 * Copyright (C) 2003 Adam J. Nelson, All Rights Reserved
 * 
 * The Double Metaphone algorithm was written by Lawrence Phillips, and is 
 * Copyright (c) 1998, 1999 by Lawrence Philips.
 **/
#include <stdafx.h>
#include "..\MetaphoneLib\ShortDoubleMetaphone.h"

#define XP_NOERROR              0
#define XP_ERROR                1
#define MAXCOLNAME				25
#define MAXNAME					25
#define MAXTEXT					255

#define ERROR_WRONG_PARAM_COUNT			1
#define ERROR_WRONG_WORD_TYPE			2
#define ERROR_WRONG_KEY_TYPE			3
#define ERROR_FAILED_GET_WORD			4
#define ERROR_METAPHONE_FAILED			5
#define ERROR_WORD_NULL					6
#define ERROR_OUTPUT_FAILED				7
#define ERROR_KEY_NOT_OUTPUT			8
#define ERROR_FAILED_GET_PARAMINFO		9
#define ERROR_MEM						10

#define	PARAM_INDEX_WORD				1
#define PARAM_INDEX_KEY1				2
#define PARAM_INDEX_KEY2				3

#ifdef __cplusplus
extern "C" {
#endif

	RETCODE __declspec(dllexport) xp_metaphone(SRV_PROC *srvproc);
	ULONG __declspec(dllexport) __GetXpVersion();
	void OutputError(SRV_PROC* srvproc, int nErrNum, LPCTSTR lpszError);

#ifdef __cplusplus
}
#endif

ULONG __declspec(dllexport) __GetXpVersion() {
	return ODS_VERSION;
}

RETCODE __declspec(dllexport) xp_metaphone(SRV_PROC *srvproc) {
	int nNumParams;
	LPSTR lpszWord = NULL;
	LPWSTR lpwszWord = NULL;
	BYTE *pData = NULL;
	BYTE bType = 0;
	ULONG uMaxLen;
	ULONG uActualLen;
	USHORT uKey1, uKey2;
	BOOL bNull;
	BOOL bUnicode;
	TCHAR szError[100];

	//Check the parameter count
	nNumParams = srv_rpcparams(srvproc);

	if (nNumParams != 3) {
		//Not the right parameters
		OutputError(srvproc, ERROR_WRONG_PARAM_COUNT, _T("xp_metaphone requires three parameters: @word varchar(255), @primaryKey smallint output, @alternateKey smallint output"));

		return XP_ERROR;
	}

	//Get the word
	if (srv_paraminfo(srvproc, PARAM_INDEX_WORD, &bType, &uMaxLen, &uActualLen, NULL, &bNull) == FAIL) {
		OutputError(srvproc, ERROR_FAILED_GET_PARAMINFO, NULL);

		return XP_ERROR;
	}

	if (bType == SRVVARCHAR || bType == SRVCHAR || bType == SRVBIGVARCHAR || bType == SRVBIGCHAR)
		bUnicode = FALSE;
	else if (bType == SRVNVARCHAR || bType == SRVNCHAR)
		bUnicode = TRUE;
	else {
		//Invalid type
		wsprintf(szError, _T("The first parameter to xp_metaphone must be a char, varchar, nchar, or nvarchar, not %d"), bType);

		OutputError(srvproc, ERROR_WRONG_WORD_TYPE, szError);
		return XP_ERROR;
	}

	if (bNull) {
		//No no 
		OutputError(srvproc, ERROR_WORD_NULL, _T("The first parameter to xp_metaphone cannot be NULL"));
		return XP_ERROR;
	}

	//Allocate space
	lpszWord = new char[uActualLen+1];

	if (!lpszWord) {
		OutputError(srvproc, ERROR_MEM, NULL);
		return XP_ERROR;
	}

	memset(lpszWord, 0, uActualLen+1);

	if (bUnicode) {
		lpwszWord = new wchar_t[uActualLen+1];

		if (!lpwszWord) {
			OutputError(srvproc, ERROR_MEM, NULL);
			delete[] lpszWord;
			return XP_ERROR;
		}

		memset(lpwszWord, 0, sizeof(wchar_t) * (uActualLen+1));

		pData = reinterpret_cast<BYTE*>(lpwszWord);
	} else
		pData = reinterpret_cast<BYTE*>(lpszWord);

	//Make sure the other two params are int2
	srv_paraminfo(srvproc, PARAM_INDEX_KEY1, &bType, &uMaxLen, &uActualLen, NULL, &bNull);

	if ((bType == SRVINTN && uMaxLen != sizeof(short)) || (bType != SRVINT2 && bType != SRVINTN)) {
		OutputError(srvproc, ERROR_WRONG_KEY_TYPE, _T("The second parameter to xp_metaphone must be a smallint"));

		delete[] lpszWord;
		if(lpwszWord) delete[] lpwszWord;
		return XP_ERROR;
	}

	srv_paraminfo (srvproc, PARAM_INDEX_KEY2, &bType, &uMaxLen, &uActualLen, NULL, &bNull);

	if ((bType == SRVINTN && uMaxLen != sizeof(short)) || (bType != SRVINT2 && bType != SRVINTN)) {
		OutputError(srvproc, ERROR_WRONG_KEY_TYPE, _T("The third parameter to xp_metaphone must be a smallint"));

		delete[] lpszWord;
		if(lpwszWord) delete[] lpwszWord;

		return XP_ERROR;
	}

	// Make sure two key params are output
	if (((srv_paramstatus(srvproc, 2) & SRV_PARAMRETURN) == FAIL) || ((srv_paramstatus(srvproc, 3) & SRV_PARAMRETURN) == FAIL)) {
		OutputError(srvproc, ERROR_KEY_NOT_OUTPUT, NULL);

		delete[] lpszWord;
		if(lpwszWord) delete[] lpwszWord;

		return XP_ERROR;
	}

	//Get the input string
	if (srv_paraminfo(srvproc, 1, &bType, &uMaxLen, &uActualLen, pData, &bNull)==FAIL) {
		OutputError(srvproc, ERROR_FAILED_GET_WORD, NULL);

		delete[] lpszWord;
		if(lpwszWord) delete[] lpwszWord;

		return XP_ERROR;
	}

	if (bUnicode) {
		//Convert from unicode
		WideCharToMultiByte(CP_ACP, 0, lpwszWord, uActualLen, lpszWord, uActualLen+1, NULL, NULL);
		delete[] lpwszWord;
		lpwszWord = NULL;
	}

	//Perform the metaphone building
	ShortDoubleMetaphone mphone(lpszWord);
	uKey1 = mphone.getPrimaryShortKey();
	uKey2 = mphone.getAlternateShortKey();

	//Free the string buffer
	delete[] lpszWord;

	//Populate the return parameters
	if (srv_paramsetoutput(srvproc, PARAM_INDEX_KEY1, reinterpret_cast<BYTE*>(&uKey1), sizeof(USHORT), FALSE) == FAIL) {
		OutputError(srvproc, ERROR_OUTPUT_FAILED, NULL);

		return XP_ERROR;
	}

	//If the alternate key was also computed, set it, else set the second key param to null
	if (uKey2 != METAPHONE_INVALID_KEY) {
		srv_paramsetoutput(srvproc, PARAM_INDEX_KEY2, reinterpret_cast<BYTE*>(&uKey2), sizeof(USHORT), FALSE);
	} else {
		srv_paramsetoutput(srvproc, PARAM_INDEX_KEY2, NULL, 0, TRUE);
	}

	return XP_NOERROR ;
}

void OutputError(SRV_PROC *srvproc, int nErrNum, LPCTSTR lpszError) {
	srv_sendmsg(srvproc, 
				SRV_MSG_ERROR,
				nErrNum,
				15,
				1,
				NULL,
				NULL,
				0,
				(lpszError?const_cast<LPTSTR>(lpszError):_T("Other error (see error number)")),
				SRV_NULLTERM);
}

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About the Author

Adam Nelson
Web Developer
United States United States
My name is Adam Nelson. I've been a professional programmer since 1996, working on everything from database development, early first-generation web applications, modern n-tier distributed apps, high-performance wireless security tools, to my last job as a Senior Consultant at BearingPoint posted in Baghdad, Iraq training Iraqi developers in the wonders of C# and ASP.NET. I am currently an Engineering Director at Dell.
 
I have a wide range of skills and interests, including cryptography, image processing, computational linguistics, military history, 3D graphics, database optimization, and mathematics, to name a few.

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