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!
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