1. Structure (i.e. struct) An structure creates a user defined data type
Contains a grouping of related data elements of arbitrary type and number
A “container” of other data elements
Individual components of the structure are called its members
Three parts to defining and using a structure
declaration of structure
use of structure to define a new variable
access of members of the structured variable

2. Structure declaration (generic)
Declare a new structure using the keyword struct
Provide a name for the new data type
List the members and their individual types
struct stype {
type1 member1;
type2 member2;
. . .
typeN memberN; };

3. Structure declaration (example)
struct student {
string firstName;
string lastName;
int age;
float GPA;
char gender;
int class; };
Creates a new data type called student
Members include:
Strings to store first and last name
Integer for student’s age and class
Float for student’s grade point average
Char for student’s gender

4. Structure usage Variable declaration Example:
Use the newly defined data type to create a variable as you would any other, built-in, data type
Access individual data members using the dot (.) operator
variable.member
Use this as you would any other variable of the given type
Example:
student S1; // variable declaration!
S1.firstName= “John”;
S1.lastName= “Doe”;
S1.age= 20;
S1.gender= ‘m’; …
// happy birthday!
S1.age+= 1;

5. structs as Operands and Arguments
struct copy or assignment
student S2= S1; // copy S1 to S2
Copies each member from S1 struct to S2 struct

6. Storage
Structure member elements are stored in sequential memory locations
Student S1
Memory Address
Member
Value
0x1xxx
firstName*
John
0x1yyy
lastName*
Doe
0x1100
age 20
0x1104
GPA
4.0
0x1108
gender** m
0x1109
class 2
* size of a string
** may actually use more than one byte

7. Passing a struct as a function argument
Argument must be of the same struct type as in the function definition/prototype
Using structs as arguments can shorten the argument list
Passing structs by value can be inefficient, since it duplicates values of all members
“pass by value” copies the entire structure

8. Passing struct by Reference
Same as any other reference parameter
use & to identify in parameter list
void printStudent(student &s)
struct members can be modified
Can also use constant reference
precede parameter with reserved word const
E.g.
void printStudent(const student &s)
const prevents the function from changing any member in the structure

9. Function printStudent()
void printStudent(const student &s) {
cout << “Student Information: " << endl;
cout << " Name : " << s.firstName << “ “ << s.lastName << endl;
cout << " Age : " << s.age << endl;
cout << " Gender : " << s.gender << endl;
cout << " Class : " << s.class << endl;
cout << " GPA : " << s.GPA << endl; }
0x1104

10. Array of Structs . Declaration of an array of structs
firstName
John
lastName
Doe
age 20
GPA
4.0
gender m
class 2
Declaration of an array of structs
student S[10];
Storage for 10 student structs
Can pass to a function
printStudent(S[i]);
Storage is in sequential memory locations
S[0]
firstName
Mary
lastName
Doe
age 21
GPA
4.0
gender f
class 3
S[1] .