Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
Try adding below header,
#include <sstream>
https://www.cplusplus.com/reference/sstream/stringstream/stringstream/
Try adding below header,
#include <sstream>
https://www.cplusplus.com/reference/sstream/stringstream/stringstream/