-C++-Lecture01Introduction12

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Computer Programming II 1

IntroductionIntroduction

Part IPart I

Lecture 1Lecture 1
http://fit.mmu.edu.my/


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ObjectivesOb

jectives

One-Dimensional ArrayTwo-Dimensional ArrayReferences

FunctionsReferences in FunctionsInline FunctionsFunction OverloadingDefault ArgumentsStructures (Records)Classes

The following topics will be discussed in this Lecture:


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Review of Arrays: One-Dimensional ArraysReview of Arra

ys: One-Dimensional Arrays

#include using namespace std;

int main(){ int item[5]item[5] ; int sum; int counter;

cout


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Review of Arrays: Two-Dimensional ArraysReview of Arra

ys: Two-Dimensional Arrays

#include #include using namespace std;

int main(){ const int NUMROWS = 3; const int NUMCOLS = 4; int i, j; int val[NUMROWS][NUMCOLS] = {8,16,9,52,

3,15,27,6,14,25,2,10};

cout


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int x = 5;

int & y = x; //ampersand sign (&) Read y is a reference to an int xint z = y;cout


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Review of FunctionsReview of Functions - Function is a block of instructions that is executed when it is called from other point of the program.

1. Function with1. Function with no return valueno return value andand no parametersn

o parameters

#include #include

using namespace std;

void SquareArea(void){ double Side;

cout > Side;cout


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int GetMajor( void )

{int Choice;cout


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#include using namespace std;

double TotPrice( double ItemPrice, double TaxRate){ double Price;

Price = ItemPrice + (ItemPrice * TaxRate / 100); return Price;}

int main(){ double ItemPrice, TaxRate;

cout > ItemPrice;cout > TaxRate;cout


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void swap( int &i, int &j);int main(){ int x = 6, y = 9;

cout


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void swap( int i, int j);int main(){ int x = 6, y = 9;

cout


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Function callsFunction calls

When a function call is encountered, the program

jumps to the address of the function and thenjumps back when the function has completed

Each time the program jumps toexecute a function, there is associatedoverhead:

Loading the function

Terminating the function call


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To help reduce function-call overhead .

Advises the compiler to generate a copy of thefunctions code in place to avoid a function call.

Should be used only with small, frequently usedfunctions.

Tradeoff: multiple copies of the function code areinserted in the program.

Inline FunctionsInline Functions

With inline functions, the compiler replaces each instanceof the function call with the corresponding code


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To define an inline function, insert thekeyword inline before the functiondefinition

inline double square ( double x) { return x * x; }


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int main(){

myFunction(2);

myFunction(5);}

Inline void myFunction( int n){

for ( int i = 0; i < n; i++){

cout


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void swap ( int &a, int &b); void swap ( float &a, float &b); void swap ( char &a, char &b);

int main(){ int i1 = 3, i2 = 5; float f1 = 3.14159f, f2 = 1.23f; char c1='A', c2='B';

cout


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#include #include


double test ( double a, double b = 7){ return a - b;}

int main ()

{ cout


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Records (Record s ( structstruct s)s)Struct is a set of diverse types of data that grouped together under aunique declaration.

The components of a struct are called the members of the struct .

The definition of struct in C++:struct student

{string firstName;

string lastName;

char courseGrade;

int testScore;

int programmingScore;

double GPA;

};

A semicolon after the right brace isessential to end the struct statement.

Variable declaration:student x;

student y;

The above two statements declare two struct variables, x and y , of the type student . Thememory allocated is large enough to storefirstName , lastName , courseGrade ,

testScore , programmingScore , and GPA .


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AccessingAcces sing structstruct MembersMembers

x.firstName = John;

x.lastName = Brown;

x.courseGrade = A;

x.testScore = 95;

x.programmingScore = 98;

x.GPA = 3.9;

To access a struct member (component), you use the struct variable name together with themember name; these namesare separated by a dot (period).

x.firstName is just like any other variable. x.firstName is a variable of the type string, x. courseGrade is a variable of the type char ,x.testScore is a int variable, and so on. As a result, you can do justabout anything with struct members that you normally do withvariables. You can, for example, use them in assignmentstatements or input/output (where permitted) statements.


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Arrays inArrays in structstruct ssArray is a set of elements of the same type. Thus, array has two things associatedwith it: the values (that is, elements), and the length. Because the values and thelength are both related to the array, we can define a struct containing both items.

const arraySize = 1000;

struct listType

{

int listElem[arraySize]; //array containing the list

int listLength; //length of the list

};

The following statement declares intList to be a struct variable of the type listType .

listType intList;

The variable intList has two members: listElem , an array of 1000 components of thetype int ; and listLength , of the type int . Moreover, intList.listElem accessesthe member listElem and intList.listLength accesses the member listLength .


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structstruct s in Arrayss in A rrays

Suppose a company has 50 full-time employees. We need to print their monthly paychecksand keep track of how much money has been paid to each employee in the year-to-date.First, lets define an employees record.

struct employeeType

{

string firstName;

string lastName; int personID;

string deptID;

double yearlySalary;

double monthlySalary;

double yearToDatePaid;

double monthlyBonus;

};

Each employee has the following members(components): first name, last name, personal ID,department ID, yearly salary, monthly salary, year-to-date paid, and monthly bonus.

Because we have 50 employees, and the datatype of each employee is the same, we can use anarray of 50 components to process the employeesdata.

employeeType employees[50];The above statement declares an arrayemployees of 50 components of the typeemployeeType . Every element of employees isa struct .


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Let us reorganize this struct as follows:

struct nameType

{string first;string middle;string last;

};

struct addressType{

string address1;string address2;string city;string state;string zip;

};

struct dateType

{ int month; int day; int year;};

struct contactType{

string phone;string cellphone;string fax;string pager;string email;

};

We have separated the employees name, address, and contact type intosubcategories. Furthermore, we have defined a struct dateType.

structstruct s within as within a structstruct


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Let us rebuild the employees record as follows:

struct employeeType{

nameType name;string empID;addressType address;dateType hireDate;dateType quitDate;contactType contact;string deptID;

double salary;};

The information in this employees struct is easier tomanage than the previous one. Some of this struct

can be reused to build another struct . For example,suppose that you want to define a customers record.Every customer has a first name, last name, andmiddle name, as well as an address and a way to becontacted. You can, therefore, quickly put together acustomers record by using the struct s nameType ,addressType , contactType , and the membersspecific to the customer.

Consider the following statement:

employeeType newEmployee;

This statement declares newEmployee to be a struct variable of the type employeeType .

The statement:

newEmployee.salary = 45678.00;

sets the salary of newEmployee to 45678.00


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The statements:

newEmployee.name.first = Mary;

newEmployee.name.middle = Beth;

newEmployee.name.last = Simmons;

set the first , middle , and last name of newEmployee to Mary , Beth , andSimmons , respectively. Note that newEmployee has a member called name . Weaccess this member via newEmployee.name . Note also that newEmployee.name is astruct and has three members. We apply the member access criteria to access themember first of the struct newEmployee.name . So newEmployee.name.first

is the member where we store the first name.The statement:

cin >> newEmployee.name.first;

reads and stores a string into newEmployee.name.first .

The statement:

newEmployee.salary = newEmployee.salary * 1.05;

updates the salary of newEmployee .


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ClassesClasses

A class is a logical method to organize data and functions in the same structure. Theyare declared using keyword class. Whose functionality is similar to keyword struct,

class Person{

public:

void setAge(unsigned n);

int getAge();

private:unsigned age;

};

The class declaration

The C++ keyword private can be used tohide class data members and methods,and the keyword public can be used toexpose class data members andmethods.


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Defining Class MethodsClass methods/functions may be implemented in two ways:

A methods may be declared inside the class declaration but implemented outside theclass declaration.

A method may be declared and implemented inside the class declaration.

class Person

{

public:

void setAge(unsigned n);int getAge();

private:

unsigned age;

};

void Person::setAge(unsigned n){ age = n; }

int Person::getAge()

{ return age; }

class Person

{

public:

void setAge(unsigned n)

{ age = n; }

unsigned getAge() const

{ return age; }

private:

unsigned age;

};

Scope resolution operator ::


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Using Classes in a Program

Classes are created to be used ultimately in Programs. Before a class can be used in a program,its declaration must be visible to any functions that are meant to use the class. Below is thecomplete program that uses the Person class.

#include


class Person

{

public:void setAge(unsigned n)

{ age = n; }

int getAge()

{ return age; }

private:unsigned age;

};

int main(){Person p; //create a single PersonPerson stooges[3]; //create an array of Persons

p.setAge(12); // set ps name// set the stooges agesstooges[0].setAge(45);stooges[1].setAge(46);stooges[2].setAge(44);// print four ages

cout


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