Storing std::string as character array

I'm trying to convert an std::string into a c string (my real problem is closer to this; I'm trying a workaround).

1. How does one store an std::string as a character array?

2. Why do std::string.data() and std::string.c_str() return char [(<anonymous> + 1)] instead of the expected const char*? Or do I have these mixed up, and if so, how do I work with these types?

   #include <string>
   #include <iostream>
   
   int main()
   {
     std::string sstring = "I'm an std string!";
   
     char cstring[sstring.size()];
   
     cstring = sstring.c_str();
     std::cout << std::string(sstring.c_str());
   
     return 0;
   }
   
   

Compilation results in

scratch.cpp:10:11: error: incompatible types in assignment of ‘const char*’ to ‘char [(<anonymous> + 1)]’

I wasn't able to find a relevant, preexisting question.