Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:71:23: error: cannot convert ‘std::string {aka std::basic_string<char>}’ to ‘char*’ for argument ‘1’ to ‘void append(char*, int)’ append(output, i); ^ user.cpp:72:14: error: ‘length’ was not declared in this scope output[length++] = '\n'; ^ user.cpp:80:13: error: ‘length’ was not declared in this scope output[length++] = '0'; ^