1. string转const char* string s = "abc"; const char* c_s = s.c_str();2. const char*转string 直接赋值即可 const char* c_s = "abc"; string s(c_s);3. string转char* string s = "abc"; char* c; const int len = s.length(); c = new char[len+1]; strcpy(c,s.c_str());4. char*转string char*