c++ presentatn

8/7/2019 C++ PRESENTATN

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ACCESS

SPECIFIERS


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A class is an expanded concept of a datastructure: instead of holding only data, it canhold both data and functions.

Classes are generally declared using thekeyword class, with the following format

class class_name {

access_specifier_1:

member1;

access_specifier_2:

member2; ...

} object_names;


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private members of a class areaccessible only f

rom within other membersof the same class or from theirfriends.

protected members are accessible frommembers of

their same class and fromtheir friends, but also from members oftheir derived classes.

Finally, public members are accessiblefrom anywhere where the object is visible.


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PRIVATE

The private keyword

specifies that thosemembers are accessibleonly from member functionsand friends of the class.


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#include

using namespace std;

class CRectangle

{

int width, height; output:

public:CRectangle (); rect area: 25

CRectangle (int,int);

int area (void) {

return (width*height); rectb area: 12

}

};

CRectangle::CRectangle ()

{ width = 5;height = 5;

}

CRectangle::CRectangle (int a, int b)

{

width = a;

height = b;

}

int main (){

CRectangle rect (3,4); // implicit call

CRectangle rectb; //calls default constructor

cout


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PUBLIC

public members are accessible from

anywhere where the object is visible

Egpublic :

int a, b;

void getdata();


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#include using namespace std;

class CRectangle

{

int x, y;public:

void setvalues (int,int);

int area () OUTPUT:

{

return (x*y); area: 12}};

void CRectangle::set_values (int a, int b)

{

x = a;

y = b;

}

int main ()

{

CRectangle rect;

rect.set_values (3,4);

cout


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PROTECTED ACCESS

SPECIFIER:

Accessible by member functionswithin its class and any classimmediately derived from it

When protected member inherited in:1. public mode : It becomes protected in

derived class

2. private mode:It becomes private inderived class

3. protected mode: It becomes protectedin derived class


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When it is appropriate for a

class's subclasses to haveaccess to the

method or field ,but not forunrelated classes.

WHEN TO USE PROTECTED ACCESS

SPECIFIER ?..


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#include

#include

class shape

{

protected:

char colour[30];

public:

void get_colour()

{

coutcolour;

cout


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class three_d:public shape

{

protected:

int c_len;

public:

void get_clen()

{

cout


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OUTPUT:Enter colour:

BLUE

Inside shape class::BLUE

Enter length for square:

20.0

Area of square : 400

Enter colour:

RED

Inside shape class::RED

Enter the lenth of cube:

25.0

Volume of cube : 15625


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#include

#include

class shape

{

protected:

char colour[30];

public:

void get_colour()

{

coutcolour;

cout


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class three_d:public shape

{

protected:

int c_len;

public:

void get_clen()

{

cout


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ErrorPROGRAM.CPP: 'shape::get_colour()' is not accessible

ERROR ISSHOWN AS:


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THANK YOU!

c++ presentatn

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