STRUCTURES OF STRUCTURES

1. STRUCTURES OF STRUCTURES Group 7 -Jorge Alejandro Chacon -Assiel Conde -Daniel Granda -Christian Tennant -How structures work and what they are. -Their purpose in a program.

2. How structures work and what they are. • The role of a structure in C programing is to group variables of different types into a single name. • A structure can be defined as a new defined type, that way we can extend the types available to us. • A structure can use other structures, arrays and pointers as members of itself. • When a structure is defined within a structure, the structure inside is called a nested structure. This is the technique we will be using.

3. Calculating the area of a rectangle program using structures • First imagine a rectangle located in the first quadrant of a 2D plane. • We will only plot 2 points that will calculate the length and width.

4. Purpose of the structures in our program • Using a structure we group the variables “x and y” which will be our coordinates to be used. • Using a nested structure we point the location where the (x,y) points input in the first structure will be plotted in our rectangle. In this case we pick the top left and bottom right. • Then we calculate the width and the length which later can be use to calculate the are by A= Length*width.

5. Bubble Diagram Gathers x and y coordinates Computes area Creates structure, calling x and y as integers Call needed libraries Calls Main() Displays the area of the rectangle using given coordinates

6. Include Libraries Calculate and print area area = width * length; printf("The area is %ld units.", area); Block Diagram Define Variables int length, width long area Calculate length and width width = mybox->bottomrt->x - mybox->topleft->x; length = mybox->bottomrt->y - mybox->topleft->y; Define structures for coord and rectangle structcoord{ int x; int y; }; struct rectangle{ structcoord *topleft; structcoord *bottomrt; Store inputs for top left x and y and bottom right x and y. printf("\nEnter the top left x coordinate: "); scanf("%d", &mybox->topleft->x); printf("\nEnter the top left y coordinate: "); scanf("%d", &mybox->topleft->y); printf("\nEnter the bottom right x coordinate: "); scanf("%d", &mybox->bottomrt->x); printf("\nEnter the bottom right y coordinate: "); scanf("%d", &mybox->bottomrt->y); Start main function

7. Highlighted parts in our code • In blue we define our variables and function. • In orange we create our first structure “coord” and we group the members “ integers x,y”. Also, we use a nested structure of “struct coord” into “struct rectangle” to point where our points (x,y) will be plotted. • In red we gather the information input by the user and we use pointer notation (->)to indicate where the information will be stored.

8. Highlighted parts in our code In blue we define our function to calculate the width and length. In red we define our function to calculate the area and print the result.

9. Sample Output

10. From our last example, we can gather that structures can easily complicate simple tasks. The example could have been drastically simplified in 16 lines vs. a whopping 46, achieving the same exact result.

11. Simpler Technique #include <stdio.h> #include <stdlib.h> int main() { int top_left_x, top_left_y, bottom_right_x, bottom_right_y; printf("Enter top left X coordinate value: "); scanf("%d", &top_left_x); printf("Enter top left Y coordinate value: "); scanf("%d", &top_left_y); printf("Enter bottom right X coordinate value: "); scanf("%d", &bottom_right_x); printf("Enter bottom Y coordinate value: "); scanf("%d", &bottom_right_y); int length = bottom_right_x - top_left_x; int width = top_left_y - bottom_right_y; int area = length * width; printf("The total area of the rectangle is: %d\n", area); return0; }

12. Sample Output

13. Second Example One appropriate use for structures is databases. They provide an effective way to gather related information, for ex.: student data for financial aid. Our next example gathers data from a student via nested structures. The student will input in the data field the following: name, panther id, gender, etc. Through the use of functions, our program will display all the collected information

14. Call needed libraries Bubble Diagram Creates structure, calling variables for employee information Calls Main() Displays stored employee information Gathers Employee Information Stores information

15. Include Libraries Block Diagram Define MAX #define MAX 1000 Display input Display(student, n) Define structures for date and school structdate{intday; int month; int year; }; struct school{ char name[20]; long intpanther_id; char sex[5]; int age; structdate dob;}; Store input CollectInformation(employee, n); Define CollectInformation and Display functions void CollectInformation(school student[MAX], int n) void Display(school student[MAX], int n) Start main function

16. Second Example struct date{ // members of structure definition int day; int month; int year; }; struct school{ char name[20]; long int panther_id; char sex[10]; int age; // nested block definition struct date dob; }; • Here we define our structures. • The structure date will include the members of type int day, month and year. • In the structure school we’ll include the char array name and will declare it to be 20 characters long. A longint for the panther ID, an int for the age and a third structure for the date of birth.

17. Highlighted parts in our code • Next, we’ll declare the object inside our structure student to have a predefined MAX amount of characters (#define MAX 1000). • An integer n is declared to gather the number of students entered. Also we create functions with the purpose of collecting and displaying the data from the user. • The function CollectInformation gathers the input, stores it in the char array student and Display will reflect contents. // structure object definition school student[MAX]; // main function starts int main(){ school student[MAX]; int n; cout << "A program that collects student information"; cout << endl; cout << "and displays the collected information"; cout << endl << endl; cout << "How many students? : "; cin >> n; cout << endl; // functions definition void CollectInformation(school student[MAX], int n); void Display(school student[MAX], int n); // functions calling CollectInformation(student, n); Display(student, n); cin.get(); return 0; }

18. Highlighted parts in our code // collecting information form the user void CollectInformation(school student[MAX], int n){ cout << "Enter the following information:"; cout << endl << endl; for (int i=1; i<=n; i++){ cout << "Enter information for student no. : " << i; cout << endl; cout << "\nName : "; cin >> student[i].name; cout << "PID : "; cin >> student[i].panther_id; cout << "Sex : "; cin >> student[i].sex; cout << "Age : "; cin >> student[i].age; cout << "Date of Birth :" << endl; cout << "Day : "; cin >> student[i].dob.day; cout << "Month : "; cin >> student[i].dob.month; cout << "Year : "; cin >> student[i].dob.year; cout << endl; } } • An integer i is looped for as many times as the amount of students entered. • Each parameter information is stored in the student array declared before with the information specified (i.e.: age, gender, etc.).

19. Highlighted parts in our code void Display(school student[MAX], int n){ cout << "Student entered information : "; cout << endl; cout << "\nName PID Sex Age Date of Birth" << endl; for (int i=1; i<=n; i++){ cout << student[i].name << "\t"; cout << student[i].panther_id << "\t"; cout << student[i].sex; cout << "\t"; cout << student[i].age; cout << "\t"; cout << student[i].dob.day << "."; cout << student[i].dob.month << "."; cout << student[i].dob.year ; cout << endl; } } • For the display function, all the information gathered before will be printed on the screen with the aforementioned parameters (i.e.: sex, age, etc.)

20. Sample Output

21. Lessons Learned • Nested structures can simplify complex code when in need to collect several pieces information that are related to each other. • One needs to be careful when creating structures since it can easily clump the main code and make it unrecognizable. • Structures have good usage in storing data, such as data in a database since different data types can be stored in them such as int, char, long, etc.