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struct Date
{int day;
int month;int year;
};
We can now use this Date type, together with other types, as members of a Student type which we can declare as follows:
struct Student
{char studentID[10];char name[30];float markCS ;
Date dateOfBirth;};
Or
struct Student
{char studentID[10];char name[30];float markCS;
struct Date {int day;
int month;int year;
} dateOfBirth;};
We can also declare structured variables when we define the structure itself:
struct Student
{char studentID[10];char name[30];float markCS ;
Date dateOfBirth;} a, b, c;
C permits to declare untagged structures that enable us to declare structure variables without defining a name for their structures. For example, the following structure definition declares the variables a, b, c but omits the name of the structure:
struct
{char studentID[10];char name[30];float markCS ;
Date dateOfBirth;} a, b, c;
A structure type cannot contain itself as a member, as its definition is not complete until the closing brace (}). However, structure types can and often do contain pointers to their own type. Such self-referential structures are used in implementing linked lists and binary trees, for example. The following example defines a type for the members of a singly linked list:
struct List
{ struct Student stu; // This record's data.struct List *pNext; // A pointer to the next student.
};
Whenever we need to refer to the members of a structure, we normally use the dot operator.
For example, if we wanted to access the number member of newStudent we could do so as follows:
newStudent.studentID
We can then access the member as if it were a normal variable. For instance, we can write to this member as follows.
newStudent.studentID= “C0681008”;
We can also read from the member in a similar fashion.
printf("Student identification: %s", newStudent.studentID);
The following code outputs the contents of an Student structure.
printf("Student Details\n");
printf("Identification: %s\n", newStudent.studentID);printf("Name: %s\n", newStudent.name);
printf("Mark: %.2f\n", newStudent.markCS);printf("Date of Birth: %i/%i/%i\n",
newStudent.dateOfBirth.day,newStudent.dateOfBirth.month,
newStudent.dateOfBirth.year);
Suppose we wish to input the details of this employee from a user. We could do so as follows.
Student newStudent;
printf("Enter student identification: ");scanf("%s",&newStudent.studentID);
printf("Enter student name: ");fflush(stdin);gets(newStudent.name);
printf("Enter mark for Introduction to computer science course: ”);scanf("%f",&newStudent.markCS);
printf("Enter birth date (dd/mm/yyyy): ");scanf("%i/%i/%i",&newStudent.dateOfBirth.day,&newStudent.dateOfBirth.month,&newStudent.dateOfBirth.year
);
When we declare a new variable of a basic data type we can initialize its value at declaration. We can also initialize structure variables at declaration as shown below.
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