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Structured Data Structured Data (Lecture 11)(Lecture 11)

By:

Dr. Norazah Yusof

FSKSM, UTM

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Data Types■ Primitive data types - defined as a basic part of the

language.

■ Abstract Data Type (ADT) – created by the programmer and is composed of one or more primitive data types.

■ Have own range (or domain) of data and own set of operations that may be performed on them.

bool int unsigned long int

char long int float

unsigned char unsigned short int double

short int unsigned int long double

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Abstract Data Type■Example: Write a program to

simulate a 12-hour clock.

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Abstract Data Type■ Example: Write a program to simulate a 12-hour

clock.■ The program could contain three ADTs:

1. Hours2. Minutes3. Seconds

■ The range of values 1. Hours : integers 1 through 122. Minutes : integers 0 through 593. Seconds : integers 0 through 59

■ If an Hours object is set to 12 and then incremented, it will then take on the value 1.

■ If an Minutes object or Seconds object is set to 59 and then incremented, it will then take on the value 0.

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Combining Data into Structures

■ Structure – group several variables together into a single item

■ Declaration format of a structure:struct tag{

variable declaration;

//more declaration;

};

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Example: Structure declaration of Timestruct Time

{

int hours;

int minutes;

int seconds;

};

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Definition of Structure Variables

■ Structure declaration does not define a variable. It only create a new data type.

■ Variable(s) of this type can be defined.

■ Format:tag varname;

■ Example: Define structure variable named now of type Time.

Time now;

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Memory layout of structure variable, now

hours

minutes

seconds

Time

Members

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Example 2■ Declare a structure named PayRoll that has the

following members:1. Employee number: integer2. Employee’s name : array of characters3. Hours worked : floating point numbers4. Hourly pay rate : floating point numbers5. Gross pay : floating point numbers

■ Define three PayRoll variables: deptHead, foreman, associate

■ Draw the memory layout.

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Example 2: Structure declaration of PayRoll and variables definition.

cont int SIZE = 25;

struct PayRoll

{

int empNumber;

char name[SIZE];

double hourWork, hourPayRate, grossPay;

};

PayRoll deptHead, foreman, associate;

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Memory Layout of PayRoll variables

empNumber

name

hourWork

deptHead

hourPayRate

grossPay

associate

empNumber

name

hourWork

hourPayRate

grossPay

foreman

empNumber

name

hourWork

hourPayRate

grossPay

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Assessing Structure Members■ Dot operator (.) allows you to access structure

members in a program.

■ Example 1: Access the empNumber member of deptHead by assigning value of 475 to it.

■ Example 2: Access the name, hourWork, and hourPayRate by assigning values of Muhammad, 200, and 15 to it, respectively. Then, assign the value to the grossPay by assigning the result of arithmetic operation: hourWork x hourPayRate

■ Example 3: Display the contents of deptHead’s member

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Assessing Structure Members

deptHead.empNumber = 475;

strcpy(deptHead.name, "Muhammad");

deptHead.hourWork = 200;

deptHead.hourPayRate = 15;

deptHead.grossPay =

deptHead.hourWork * deptHead.hourPayRate;

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Assessing Structure Members

■ Example 3: Display the contents of deptHead’s member.– Cannot display the content by passing the entire

variable:

cout << deptHead; //will not work!

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Assessing Structure Members■ Example 3: Display the contents of deptHead’s member. Each member must be passed to cout, separately.

cout << "Name: " << deptHead.name << endl;

cout << "ID Number: " << deptHead.empNumber << endl;

cout << "Hours worked: " << deptHead.hourWork;

cout << endl;

cout << "Hourly pay rate: " << deptHead.hourPayRate;

cout << endl;

cout << "Gross pay: " << deptHead.grossPay << endl;

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Read data from the keyboard

■Change Example 2: Read data from the keyboard for the members name, hourWork, and hourPayRate.

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Read data from the keyboardcout << "Enter the employee number:";

cin >> deptHead.empNumber; cout << "Enter the employee’s name:"; cin.ignore();

//ignore the next character in // the input buffer.

cin.getline(deptHead.name, SIZE); cout << "How many hours did the employee work?"; cin >> deptHead.hourWork; cout << "What is the employee’s hourly pay rate?"; cin >> deptHead.hourPayRate;

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Comparing Structure Variables■ Cannot perform comparison operations

directly on structure variables. if (deptHead == foreman) //Error!

■ To compare between two structures, need to compare individual members, as follows: if (deptHead.hourWork == foreman.hourWork) :if (strcmp(deptHead.name,foreman.name) == 0) :

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Initializing a Structure

■ The members of a structure variable may be initialized with starting values when it is defined.

■ Example: Declare a structure variable named CityInfo. Define a variable named location with initialization values. structure CityInfo{ char cityName[30]; char state[3]; long population; int distance;};

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Initializing a Structure

structure CityInfo{ char cityName[30]; char state[3]; long population; int distance;};i. CityInfo location = {"Johor Bahru", "JH", 80000, 280};

ii. CityInfo location = {"Kuantan", "PH", 50000};iii. CityInfo location = {"Ipoh", "PK"};iv. CityInfo location = {"Kuala Terengganu"};v. CityInfo location = {"Seremban", "NS", ,68};//illegal!