Struct

Objective #1: Understand what structures are and how to use them.

• Structures are used in C++ to group variables together in order to make one's programming task more efficient. Any combination of variables and arrays can be combined into one structure. This is a useful and efficient way to store data. For example, the structure

  struct  Student
  {
         apstring socSecNum;
         apstring lastName;
         apstring firstName;
         int pointsEarned;
         double gpa;
  };

  allows the programmer to keep related data referring to individual students together. Notice that this example groups strings, integer, and double variables together into one structure. Each of the different variables are called members of the structure.
  
      You still need to create an actual variable of the type, Student, before you make use of this structure. This would be done with a statement like,
  
      Student freshmen;       
  
  which creates a variable called freshmen of the type Student (which happens to be a structure as opposed to an int or a float.) Then, to assign a GPA of 3.4 to the GPA field of the variable, freshmen, you would use the statement,   
  
  freshmen.gpa = 3.4;    
  
  The period symbol (.) that is used between the structure identifier, freshmen, and the member, GPA, is called the dot operator. The dot operator simply allows the programmer to reference individual members of a structure.

• It is possible to nest a structure inside of another structure. They are called nested structures in this case. That is, one struct variable can be a member of another struct variable.
  
  Example -
  
  struct Name
  {
       string firstName;
       string lastName;
  };
  
  struct Student
  {
        Name wholeName;
        string socSecNum;
        int pointsEarned;
        double gpa;
  };
  
  
• The struct definition for Name must appear before the struct definition for Student since the compiler must know what a Name is since it is used within the definition of a Student.
  
  
• To refer to one of the members of the nested structure it is necessary to use the dot operator twice as in the following example:
  
  Student classClown;
  classClown.wholeName.firstName = "Robert";