main3.cpp: In constructor 'cmps2020_student::cmps2020_student(std::string, int)':
main3.cpp:14:17: error: 'age' was not declared in this scope; did you mean '_age'?
   14 |                 age=_age;
      |                 ^~~
      |                 _age
main3.cpp: In function 'int main()':
main3.cpp:25:11: error: no match for 'operator<' (operand types are 'cmps2020_student' and 'cmps2020_student')
   25 |    if ( a < b)
      |         ~ ^ ~
      |         |   |
      |         |   cmps2020_student
      |         cmps2020_student