string s;
char* p="hello";
char a[]="hello";
 
s=p;
s=a;

// 1
string str="hello";
const char*　p=str.data();
char* p=(char*)str.data();

// 2
string str="world";
const char* p=str.c_str();
char* p=(char*)str.c_str();

// 3
string str="test";
char array[50];
str.copy(array,48,0);  //48代表数组长度,0代表起始位置
array[49]=' ';        //添加结束符
 
char* p=new char[50]();
str.copy(p,48,0);
*(p+49)=' ';

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;      
}