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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;
}

#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;

}
三 C++ 的字符串与C#的转化

1）将system::String 转化为C++的string：

// convert_system_string.cpp

// compile with: /clr

#include <string>

#include <iostream>

using namespace std;

using namespace System;

void MarshalString ( String ^ s, string& os )

{

using namespace Runtime::InteropServices;

const char* chars =

(const char*)(Marshal::StringToHGlobalAnsi(s)).ToPointer();

os = chars;

Marshal::FreeHGlobal(IntPtr((void*)chars));

}

void MarshalString ( String ^ s, wstring& os )

{

using namespace Runtime::InteropServices;

const wchar_t* chars =

(const wchar_t*)(Marshal::StringToHGlobalUni(s)).ToPointer();

os = chars;

Marshal::FreeHGlobal(IntPtr((void*)chars));

}

int main()

{

string a = "test";

wstring b = L"test2";

String ^ c = gcnew String("abcd");

cout << a << endl;

MarshalString(c, a);

c = "efgh";

MarshalString(c, b);

cout << a << endl;

wcout << b << endl;

}

2）将System::String转化为char*或w_char*

// convert_string_to_wchar.cpp

// compile with: /clr

#include < stdio.h >

#include < stdlib.h >

#include < vcclr.h >

using namespace System;

int main()

{

String ^str = "Hello";

// Pin memory so GC can't move it while native function is called

pin_ptr<const wchar_t> wch = PtrToStringChars(str);

printf_s("%S\n", wch);

// Conversion to char* :

// Can just convert wchar_t* to char* using one of the

// conversion functions such as:

// WideCharToMultiByte()

// wcstombs_s()

etc

size_t convertedChars = 0;

size_t sizeInBytes = ((str->Length + 1) * 2);

errno_t err = 0;

char *ch = (char *)malloc(sizeInBytes);

err = wcstombs_s(&convertedChars,

ch, sizeInBytes,

wch, sizeInBytes);

if (err != 0)

printf_s("wcstombs_s failed!\n");

printf_s("%s\n", ch);

}