Basic SSO string

sso_string.cpp

#include <cassert>
#include <cstddef>
#include <string>

template <int8_t len>
class string {
  private:
    char arr[len + 1];
    
  public:
    string() { arr[len - 1] = len; }
    
    uint8_t size() const noexcept { return static_cast<uint8_t>(len - arr[len - 1]); }
    
    void operator=(const std::string& s) {
      // no check for overflow
      for (std::size_t i { 0 }; i < s.size(); i++) {
        arr[i] = s[i];
      }
      
      arr[len - 1] = len - s.size();
    }
};

int main() {
  string<3> s;
  
  s = "a";
  
  assert(s.size() == 1);
}