[Windows 8] How to covert Platform::String to char and fix C2440 Error with C++

Covert Platform::String to char
        Platform::String ^SrcString = "abc";
        std::wstring tmpW(SrcString ->Begin());
std::string tmpA(tmpW.begin(), tmpW.end());
char* DstString = tmpA.c_str();     // Error C2240

fix C2440 Error

        Platform::String ^SrcString = "abc";

        std::wstring tmpW(SrcString ->Begin());
std::string tmpA(tmpW.begin(), tmpW.end());
const char* DstString = tmpA.c_str();