Unicode编码下字符串转换

VC\MFC当中CString、string、char、char*、char数组、int等类型之间的转换令人晕头转向，特地搜集多篇文章资料，利用代码实例等清晰的理清他们之间的关系和如何转换，其实非常简单。

1、CString std::string互转
std::string strstring = "std::string";
CString strCString = _T("CString");

//CString->std::string
strstring = CStringA(strCString);

//std::string->CString
strCString = strstring.c_str();

2、int和CString
//CString->int
CString strInt = _T("123");
int n = 0;
n = _ttoi(strInt);
n = 9;
//int->CString
strInt.Format(_T("%d"), n);

3、double和CString
CString strdouble = _T("123.00");
double dVal = 0;
//CString->double
dVal = _tstof(strdouble);
dVal = 999.0;
//double->CString
strdouble.Format(_T("%f"), dVal);

//4、char*和CString
char* chchar = "chahdaslhdf";
CString strCh = _T("char");
//char*->CString
strCh = chchar;
//或者
//预转换，得到所需空间的大小
int wcsLen = ::MultiByteToWideChar(CP_ACP, NULL, chchar, strlen(chchar), NULL, 0);
//分配空间要给'\0'留个空间，MultiByteToWideChar不会给'\0'空间
wchar_t* wszString = new wchar_t[wcsLen + 1];
//转换
::MultiByteToWideChar(CP_ACP, NULL, chchar, strlen(chchar), wszString, wcsLen);
//最后加上'\0'
wszString[wcsLen] = '\0';
//附加到CString对象上
CString content;
content.Append(wszString);

//CString->char*
int n = strCh.GetLength(); //按字符计算，strCh的长度

int len = WideCharToMultiByte(CP_ACP, 0, strCh, n, NULL, 0, NULL, NULL);//按Byte计算str长度
char *pChStr = new char[len+1];//按字节为单位
memset(pChStr,0,len+1);
WideCharToMultiByte(CP_ACP, 0, strCh, n, pChStr, len, NULL, NULL);//宽字节转换为多字节编码
pChStr[len] = '\0';
memcpy(chDis, pChStr, len + 1);
delete []pChStr;

CString转char*

char* ch = new char;
CString str1 = _T("12121");
strcpy(ch, CStringA(str1).GetString());

5、将wchar_t*转化为char*

char* UnicodeToAnsi(const wchar_t* szStr)
{
    int nLen = WideCharToMultiByte( CP_ACP, 0, szStr, -1, NULL, 0, NULL, NULL );
    if (nLen == 0)
    return NULL;

char* pResult = new char[nLen+1];
    WideCharToMultiByte( CP_ACP, 0, szStr, -1, pResult, nLen, NULL, NULL );
    return pResult;
}

6、将char*转化为wchar_t*

wchar_t* AnsiToUnicode(const char* szStr)
{
    int nLen = MultiByteToWideChar( CP_ACP, MB_PRECOMPOSED, szStr, -1, NULL, 0 );
    if (nLen == 0)
    return NULL;

wchar_t* pResult = new wchar_t[nLen+1];
    MultiByteToWideChar( CP_ACP, MB_PRECOMPOSED, szStr, -1, pResult, nLen );
    return pResult;
}

7、头文件#include <sstream>
//int->string
int n1 = 0;
std::stringstream ssCov;
std::string str;
ssCov<<n1;
ssCov>>str;

//string->int
std::string strNum = "123";
int n2 = atoi(strNum.c_str());