class student class student { private: string id; string firstname, lastname; float gpa; public:...

Class Studentclass Student

{

private:

string id;

string firstName, lastName;

float gpa;

public:

void Read()

void Write()

string getGPA()

void setGPA( float value )

void updateGPA( float amount )

. . .

};

// Student is a data type

// Data and functions together1

Class and Object

// Declare variable and reserve memory spaceint numStudents;

// Declare class variable// memory space for data fields// methodsStudent s1;

// Input data into object s1s1.Read();

// No values for data memberss1.Write();

2

Initial Values

// Declare variable with initial valueint numStudents = 0;

// Can we declare class variable with initial value?Student s1;

Use Class Constructors!

3

Class Default Constructorclass Student

{

private:

string id;


float gpa;

public:

Student()

{

id = “12345”;

firstName = “first”;

lastName = “last”;

gpa = 2.5;

}

};

// Syntax for constructor

// Default constructor has no parameters4

Default Class Constructor

// Default constructor is calledStudent s1;

// The default constructor has set the // values for data memberss1.Write();

// This will change the data fieldss1.Read();

// Output data of object s1s1.Write();

Constructor is called implicitly when class variables are declared.

5

Constructor with Parameters

class Student

{

private:

string id;


float gpa;

public:

Student(string sID, string first, string last, float g)

{

id = sID;

firstName = first;

lastName = last;

gpa = g;

}

};

6

Constructor with Parameters

// Class constructor is calledStudent s1(“12345”, “John”, “Smith”, 2.8);

// The constructor has set the // values for data memberss1.Write();

// This will change gpas1.UpdateGPA(0.1);

// Output data of object s1s1.Write();

7

Class Constructors with Different Parameters

class Student

{

private:

. . .

public:

Student(string sID)

{

id = sID;

// could set other default values

}

Student(string first, string last)

{

firstName = first;

lastName = last;

gpa = 2.5; // can still set gpa

}

};8

Class Constructors

// Student(string sID) is calledStudent s1(“56789”);

// Student(string first, string last) is calledStudent s2(“Qi”, “Yang”);

// Student(String sID, string first, string last, // float g) is calledStudent s3(“13579”, “Joe”, “Clifton”, 3.9);

// Student() is calledStudent s4();

9

Different Constructors Must Have Different Parameters

class Student

{

private:

. . .

public:

Student(string last, string first)

{

firstName = first;

lastName = last;

}


{

firstName = first;

lastName = last;

}

};

Will this work?10

Different Constructors Must Have Different Parameters

// Which one will be called?// Student(string first, string last)// Student(string last, string first)Student s(“Qi”, “Yang”);

11

Different Parameters:Different Type

class Student

{

private:

. . .

public:

Student(string last, string first)

{

firstName = first;

lastName = last;

}

Student(string sID, float g)

{

id = sID;

gpa = g;

}

};12

Different Parameters:Different Type

// Student(string first, string last) is calledStudent s(“Qi”, “Yang”);

// Student(string sID, float g) is calledStudent s(“12345”, 3.3);

13

Class Constructors

class Student

{

private:

. . .

public:

Student()

Student(string sID)




};

14

Class Constructors




// Student() is calledStudent s4();


15

No Default Constructor

class Student

{

private:

. . .

public:

// Student()

Student(string sID)




};

16

No Default Constructor





// No default constructor if a constructor is defined.Student s4();

17

No Constructors

class Student

{

private:

. . .

public:

/*

Student()

Student(string sID)




*/

};

18

Class Constructors// InvalidStudent s1(“56789”);

// InvalidStudent s2(“Qi”, “Yang”);

// InvalidStudent s3(“13579”, “Joe”, “Clifton”, 3.9);

// InvalidStudent s(“12345”, 3.3);

// Default constructor is good!Student s4();

// Will not work!s4.Write();s4.UpdateGPA( 0.1 );

19

Copy Constructor

class Student

{

private:

string id, firstName, lastName;

float gpa;

public:


// Copy constructor:

// gets initial values from object s

Student( Student s)

{

id = s.id;

firstName = s.firstName;

lastName = s.lastName;

gpa = s.gpa;

}

};20

Class Constructors


int x, y = 10;

// Copy constructor is calledStudent s2(s1);

// Similar to the copy constructorx = y;

s2.Write();

s2.UpdateGPA( 0.1 );

s2.Write();21

Schedule

• Quiz7-2: Due Wednesday

• Program 5

Pairs by Wednesday

22

23

Test 1

Test 2

Test 3

FinalFinal

24

Good Luck!

• Come to classes/labs

• Do the work by yourself

• Get Help

class student class student { private: string id; string firstname, lastname; float gpa; public:...

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