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php爱好者> php文档> C++中各种string的相互转化

C++中各种string的相互转化

时间：2010-06-22 来源：yf956613

因工作需要要进行LPCWSTR和string的转换，到网上搜出一篇详细介绍的文章出来了，本着“拿来主义”做个技术积累。

一 C++ 中 string与wstring互转

方法一：

string WideToMutilByte(const wstring& _src)
{
int nBufSize = WideCharToMultiByte(GetACP(), 0, _src.c_str(),-1, NULL, 0, 0, FALSE);

char szBuf = new char[nBufSize];

WideCharToMultiByte(GetACP(), 0, _src.c_str(),-1, szBuf, nBufSize, 0, FALSE);

string strRet(szBuf);

delete []szBuf;
szBuf = NULL;

return strRet;
}

wstring MutilByteToWide(const string& _src)
{
//计算字符串 string 转成 wchar_t 之后占用的内存字节数
int nBufSize = MultiByteToWideChar(GetACP(),0,_src.c_str(),-1,NULL,0);

//为 wsbuf 分配内存 BufSize 个字节
wchar_t wsBuf = new wchar_t[nBufSize];

//转化为 unicode 的 WideString
MultiByteToWideChar(GetACP(),0,_src.c_str(),-1,wsBuf,nBufSize);

wstring wstrRet(wsBuf);

delete []wsBuf;
wsBuf = NULL;

return wstrRet;
}

转载：csdn

这篇文章里，我将给出几种C++ std::string和std::wstring相互转换的转换方法。

第一种方法：调用WideCharToMultiByte()和MultiByteToWideChar()，代码如下（关于详细的解释，可以参考《windows核心编程》）：

#include <string>

#include <windows.h>

using namespace std;

//Converting a WChar string to a Ansi string

std::string WChar2Ansi(LPCWSTR pwszSrc)

{

int nLen = WideCharToMultiByte(CP_ACP, 0, pwszSrc, -1, NULL, 0, NULL, NULL);

if (nLen<= 0) return std::string("");

char* pszDst = new char[nLen];

if (NULL == pszDst) return std::string("");

WideCharToMultiByte(CP_ACP, 0, pwszSrc, -1, pszDst, nLen, NULL, NULL);

pszDst[nLen -1] = 0;

std::string strTemp(pszDst);

delete [] pszDst;

return strTemp;

}

string ws2s(wstring& inputws)

{

return WChar2Ansi(inputws.c_str());

}

//Converting a Ansi string to WChar string

std::wstring Ansi2WChar(LPCSTR pszSrc, int nLen)

{

int nSize = MultiByteToWideChar(CP_ACP, 0, (LPCSTR)pszSrc, nLen, 0, 0);

if(nSize <= 0) return NULL;

WCHAR *pwszDst = new WCHAR[nSize+1];

if( NULL == pwszDst) return NULL;

MultiByteToWideChar(CP_ACP, 0,(LPCSTR)pszSrc, nLen, pwszDst, nSize);

pwszDst[nSize] = 0;

if( pwszDst[0] == 0xFEFF) // skip Oxfeff

for(int i = 0; i < nSize; i ++)

pwszDst[i] = pwszDst[i+1];

wstring wcharString(pwszDst);

delete pwszDst;

return wcharString;

}

std::wstring s2ws(const string& s)

{

return Ansi2WChar(s.c_str(),s.size());

}

第二种方法：采用ATL封装_bstr_t的过渡：（注，_bstr_是Microsoft Specific的，所以下面代码可以在VS2005通过，无移植性）；

#include <string>

#include <comutil.h>

using namespace std;

#pragma comment(lib, "comsuppw.lib")

string ws2s(const wstring& ws);

wstring s2ws(const string& s);

string ws2s(const wstring& ws)

{

_bstr_t t = ws.c_str();

char* pchar = (char*)t;

string result = pchar;

return result;

}

wstring s2ws(const string& s)

{

_bstr_t t = s.c_str();

wchar_t* pwchar = (wchar_t*)t;

wstring result = pwchar;

return result;

}

第三种方法：使用CRT库的mbstowcs()函数和wcstombs()函数，平台无关，需设定locale。

#include <string>

#include <locale.h>

using namespace std;

string ws2s(const wstring& ws)

{

string curLocale = setlocale(LC_ALL, NULL); // curLocale = "C";

setlocale(LC_ALL, "chs");

const wchar_t* _Source = ws.c_str();

size_t _Dsize = 2 * ws.size() + 1;

char *_Dest = new char[_Dsize];

memset(_Dest,0,_Dsize);

wcstombs(_Dest,_Source,_Dsize);

string result = _Dest;

delete []_Dest;

setlocale(LC_ALL, curLocale.c_str());

return result;

}

wstring s2ws(const string& s)

{

setlocale(LC_ALL, "chs");

const char* _Source = s.c_str();

size_t _Dsize = s.size() + 1;

wchar_t *_Dest = new wchar_t[_Dsize];

wmemset(_Dest, 0, _Dsize);

mbstowcs(_Dest,_Source,_Dsize);

wstring result = _Dest;

delete []_Dest;

setlocale(LC_ALL, "C");

return result;

}

二 utf8.utf16.utf32的相互转化

可以参考Unicode.org 上有ConvertUTF.c和ConvertUTF.h （下载地址：http://www.unicode.org/Public/PROGRAMS/CVTUTF/）

实现文件ConvertUTF.c：（.h省）

/**//*

* Disclaimer

* This source code is provided as is by Unicode, Inc. No claims are

* made as to fitness for any particular purpose. No warranties of any

* kind are expressed or implied. The recipient agrees to determine

* applicability of information provided. If this file has been

* purchased on magnetic or optical media from Unicode, Inc., the

* sole remedy for any claim will be exchange of defective media

* within 90 days of receipt.

* Limitations on Rights to Redistribute This Code

* Unicode, Inc. hereby grants the right to freely use the information

* supplied in this file in the creation of products supporting the

* Unicode Standard, and to make copies of this file in any form

* for internal or external distribution as long as this notice

* remains attached.

/**//* ---------------------------------------------------------------------

Conversions between UTF32, UTF-16, and UTF-8. Source code file.

Author: Mark E. Davis, 1994.

Rev History: Rick McGowan, fixes & updates May 2001.

Sept 2001: fixed const & error conditions per

mods suggested by S. Parent & A. Lillich.

June 2002: Tim Dodd added detection and handling of incomplete

source sequences, enhanced error detection, added casts

to eliminate compiler warnings.

July 2003: slight mods to back out aggressive FFFE detection.

Jan 2004: updated switches in from-UTF8 conversions.

Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.

See the header file "ConvertUTF.h" for complete documentation.

------------------------------------------------------------------------ */

#include "ConvertUTF.h"

#ifdef CVTUTF_DEBUG

#include <stdio.h>

#endif

static const int halfShift = 10; /**//* used for shifting by 10 bits */

static const UTF32 halfBase = 0x0010000UL;

static const UTF32 halfMask = 0x3FFUL;

#define UNI_SUR_HIGH_START (UTF32)0xD800

#define UNI_SUR_HIGH_END (UTF32)0xDBFF

#define UNI_SUR_LOW_START (UTF32)0xDC00

#define UNI_SUR_LOW_END (UTF32)0xDFFF

#define false 0

#define true 1

/**//* --------------------------------------------------------------------- */

ConversionResult ConvertUTF32toUTF16 (

const UTF32** sourceStart, const UTF32* sourceEnd,

UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags)

{

ConversionResult result = conversionOK;

const UTF32* source = *sourceStart;

UTF16* target = *targetStart;