text: //write include required statements
  #include<string>
  
  //Write a function prototype named get_grade_points that accepts a string letter_grade and returns
  //an int.
  int get_grade_points(std::string letter_grade);
  
  
  //Write a function prototype with name calculate_gpa that accepts an int named credit_hours and
  //an double named credit_points returns double.  
  double calculate_gpa(int credit_hours, double credit_points);
  
  std::string get_letter_grade_using_if(int num);
  
  std::string get_letter_grade_using_switch(int num);
  
  