C++的字符串转换和文件操作

字符串转换：

1.wstring转string

string WCharToAnsi(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 WCharToAnsi(inputws.c_str()); }

2.string转wstring

std::wstring Ansi2WChar(LPCSTR pszSrc, int nLen)
{
    int nSize = MultiByteToWideChar(CP_ACP, 0, (LPCSTR)pszSrc, nLen, 0, 0);
    if(nSize <= 0) return L"";
    WCHAR *pwszDst = new WCHAR[nSize+1];
    if( NULL == pwszDst) return L"";
    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;
}

3.wstring转UTF8

 

string WCharToUTF8(wstring strUnicode)
{
    //MessageBox(strUnicode);
    int ilen = WideCharToMultiByte(CP_UTF8, 0, strUnicode.c_str(), -1, NULL, 0, NULL, NULL);
    char *szUtf8Temp=new char[ilen + 4];
    memset(szUtf8Temp, 0, ilen + 4);
    szUtf8Temp[0] = 0xEF;
    szUtf8Temp[1] = 0xBB;
    szUtf8Temp[2] = 0xBF;
    WideCharToMultiByte (CP_UTF8, 0, strUnicode.c_str(), -1, &szUtf8Temp[3], ilen, NULL,NULL);
    ilen += 3;
    szUtf8Temp[ilen - 1] = 0;
    std::string strTemp(szUtf8Temp);
    delete [] szUtf8Temp;
    return strTemp;
}

4.UTF8转wstring

wstring UTF8ToWChar(LPCSTR pszSrc, int nLen)
{
    int nSize = MultiByteToWideChar(CP_UTF8, 0, (LPCSTR)pszSrc, nLen, 0, 0);
    if(nSize <= 0) return L"";
    WCHAR *pwszDst = new WCHAR[nSize+1];
    if( NULL == pwszDst) return L"";
    MultiByteToWideChar(CP_UTF8, 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;
}

文件操作：

1.格式化文件大小

#include <sstream>
#include <iomanip>
#ifdef UNICODE
#define tstring std::wstring
#define tostringstream std::wostringstream
#else
#define tstring std::string
#define tostringstream std::ostringstream

#endif

std::wstring FormatFileSize( size_t nSize )
{
    tostringstream oss;
    oss<<setiosflags(ios::fixed)<<setiosflags(ios::right)<<setprecision(2);

    if (nSize > 1024*1024*1024)
        oss << (double)nSize/1024/1024/1024 <<  tstring(_T("GB"));
    else if (nSize > 1024*1024)
        oss << (double)nSize/1024/1024 <<  tstring(_T("MB"));
    else if (nSize > 1024)
        oss << (double)nSize/1024 <<  tstring(_T("KB"));
    else if (nSize > 0)
        oss << nSize << tstring(_T("B"));
    else
        oss << tstring(_T("未知"));
    return oss.str();
}

2.获取文件名和扩展名

// 获取文件名
wstring GetFileName(wstring strFilename)
{
    int npos = strFilename.rfind('\\');
    return strFilename.substr(npos == string::npos ? strFilename.length() : npos+1);
}

// 获取扩展名
wstring GetFileExt(wstring strFilename)
{
    int npos = strFilename.rfind('.');
    return strFilename.substr(npos == string::npos ? strFilename.length() : npos+1);
}