It is initially called as “C with classs”.
created by Bjarne stroustrup in 1979 at Bell laboratories, NJ.
#include <iostream>
using namespace std;
int main() {
cout << "Hello, World!" << endl;
return 0;
}
Names that are used to refer variable,fucntion, label and various other user defined objects
All predefined words 48 keywords in C++
auto Double switch else enum
break Extern float For register
case typedef return union goto
char Const goto short unsigned
continue If signed sizeof void
int static volatile do Long
struct While asm New operator
template private this protected throw
catch public try Class friend
virtual Inline delete
Note: Datatype, operators, constant, variables are nearly same to C
which is not change during program const int raj=23;
// Constant: a value that does not change during the program
const int raj = 23; // constant integer variable named 'raj'
class Rajesh {
const Rajesh obj; // constant object of class Rajesh
void rajesh() const{} // constant member function named 'rajesh'
void arun() const; // declaration of a constant member function named 'arun'
};
class MyClass {
public:
// Constructor with member initialization list
MyClass(int a, int b)
: regVar(a), constVar(b)
{}
private:
int regVar; // Regular integer member variable
const int constVar; // Constant integer member variable
};
Instance of type class
Specification of object contains data members and fucntions
Separate file for classes- we need to add rajesh.h rajesh.cpp
Certainly, I’ll revamp the notes into a clearer structure:
#ifndef RAJESH_H
#define RAJESH_H
class Rajesh {
public:
Rajesh(); // Constructor declaration
protected:
private:
// Declare any private member variables here
};
#endif // RAJESH_H
rajesh.cpp
#include "rajesh.h"
// Constructor definition
Rajesh::Rajesh() {
// Constructor implementation
}
main.cpp
#include <iostream>
#include "rajesh.h" // Include the header file for class declaration
using namespace std;
int main() {
Rajesh obj; // Create an object of class Rajesh
return 0;
}
to get the variable, methods from particular class
used to delete a object ~r (cannot be overload, cant have any parameters)
The arrow member selection operator(->): whe pointer is using instead of objects
MyClass obj;
MyClass *ptr = &obj;
ptr->myPrint();
We can intialize it in two methods one normal and another syntax —-classname():variable(45){}
#include <iostream>
using namespace std;
class Cube
{int side; public: Cube(); };
Cube::Cube(){side=89}
int main() {Cube c; cout << c.side; return 0;}
#include <iostream>
using namespace std;
class Cube{
public:
int side;
Cube(int); };
Cube::Cube(int n)
{side=n; }
int main()
{Cube c(5);
cout<<c.side; return 0;}
#include <iostream.h>
Using namespace std;
Class rectangle{int width, int height;
Public: rectangle();rectangle(int,int); int area(){return (width*height);}}
rectangle::rectangle(int a, int b){width=a;height=b;}
rectangle::rectangle(){width=5;height=6;}
int main() {rectangle obj1(2,4);rectangle obj2; cout<<obj1 area(); cout<<obj2.area();} //Constructor overloading
int main(){rectangle obj1; rectangle onj2=obj1;} // is copy constructor
*Static member fucntion only can access static member variable
void func(int a, int a, int c){a=+1;b=+1;c=+1;} int main(){int x=1,y=2,z=3; func(x,y,z);} ///passing by valuevoid func(int &a, int &b, int &c){a=+1;b=+1;c=+1;}
int main(){int x=1,y=2,z=3; func(x,y,z);} //passing to reference
Pass by address void func(int *p){*p=3;} int main(){int a=4; func(&a);}
//passing address
Default values in parameter void add(a,b=4){c=a+b;return(c);} main(){add(3,7);} // 7 dan b value, if u not give any value it take 4
Inline function – same as other normal functions just reduce time only used in short functions not in long functions
Friend funtion:Public and protected function of class can be access from outside of same class
#include <iostream.h>
Using namesapce std;
Class Box{int width;
friend void printfunc(Box box);//to access object dot operator
Private: void getfunc(double wid);}
Box:: void getfunc(double wid){ wid=width;}
Void printfunc(Box box){ cout<<box.width }//access privte
Int main(){Box box; box.getfunc(83.5); printfunc(box); getch();}
Optional parameter: we give value in function func(int n=5);
Dynamic memory allocation- pointer=new type[i]; delete[]p;
Allows us to define a class in terms of another class, instead of writing completely new data members and member functions
#include <iostream>
using namespace std;
class rajesh{
public:
int lenght,width;
int setting(int l, int w){lenght=l;width=w;}};
class rajesh2:public rajesh
{public: int output(){return (lenght*width);}};
int main()
{rajesh2 m;
m.setting(2,3);
cout<<m.output();
return 0;}
*if constructor is beed inherited , construtor of base class first occur and construtor of derived class is execute and it is reverse in case of destrutor
#include <iostream>
using namespace std;
class rajesh{
public:
rajesh(){cout<<"iam constructor 1"<<endl;}};
class rajesh2:public rajesh
{public: rajesh2(){cout<<"iam construtor 2";}};
int main(){
rajesh2 m;
return 0;}
#include <iostream>
using namespace std;
class a{
public:
int x;
virtual int f(){cout<< "hii baby a"<<endl;}};
class b: public a
{public: int f() {cout<<"hii b"<<endl;}};
class c: public b
{public: int f() {cout<<"hii c";}};
int main(){ a ao; b bo; c co;
a* aptr=&ao; aptr->f();
aptr=&bo; aptr->f();
aptr=&co; aptr->f();}
class rajesh{ public:int a,b,c; rajesh(int A,int B,int C){a=A;b=B;c=C;} int display(){cout«a«b«c«endl;}
void operator -(){a=-a;b=-b;c=-c;} };
int main(){ rajesh m(9,5,6); m.display(); -m; -m.display(); }
## Virtual function:
> two function having same will call virtual first and then other
Pure virtual function: is vitual function which has no body. Class contains atleast one pure virtual function is called abstract base class // virtual int f()=0;
```cpp
Template function: userdefined datatype.// template<class T>
T fun(T a,T b){
return c+b;
//template<class T> class classname{}
concept that binds together the data and functions that manipulate the data, and that keeps both safe from outside interference and misuse. Data encapsulation led to the important OOP concept of data hiding.
class Adder{
public:
// constructor
Adder(int i = 0){total = i;}
// interface to outside world
void addNum(int number)
{total += number;}
// interface to outside world
int getTotal() {return total; };
private:
// hidden data from outside world
int total; };
int main( )
{ Adder a;
a.addNum(10);
a.addNum(20);
a.addNum(30);
cout << "Total " << a.getTotal() <<endl;
return 0;}
Data abstraction is a mechanism of exposing only the interfaces and hiding the implementation details from the user.(representing the implementation)
is a mechanism of bundling the data, and the functions that use them (wraaping the implementation)
<<reading, >>writing, ios::in //open a file for reading ios::out>>open a file for writing
Ios::trunc //if file already exist content will truncated before opening file
Ios::app //append content to end of the file
#include <iostream>
#include <fstream>
using namespace std;
int main(){
char data[100];
ofstream m;
m.open("rajesh.txt");
cout<<"hii baby enter the datas okko"<<endl;
cout<<"enter the name"<<endl;
cin>>data;
m<<data;
m.close();
ifstream n;
n.open("rajesh.txt");
cout<<"hii machi"<<endl;
n>>data;
cout<<data;
n.close();
return 0;}
when possible to come using two same named function , we use namespace
Namespace first_space{void fucn(){//info}}
Namespace second_space{void fucn(){//info}}
Main(){
First_space::func();
second_space::func();
}
Or
Namespace first_space{void fucn(){//info}}
Namespace second_space{void fucn(){//info}}
Using namespace first_space;
Main(){
func();
}
Handles error in the program. Try, catch, throw
try {int motherAge = 29, sonAge = 36;
if (sonAge > motherAge) { throw 99; }}
catch (int x) {
cout<<"Wrong age values - Error "<<x;
} //Outputs "Wrong age values - Error 99"
Catch(…)// catch all exceptions
#include <iostream>
#include <fstream>
using namespace std;
int main() {
ofstream MyFileobj; //to open file
MyFileobj.open("test.txt");
MyFileobj << "Some text. \n";
if (MyFileobj.is_open()) {
MyFileobj << "This is awesome! \n";}
else {cout << "Something went wrong";}
MyFileonj.close(); //close file
}