C++ programming tutorial 5

 Call by value or reference -

There are two type in function call by value or call by reference in it we pass the value in call by value we pass value and in call by reference we pass the reference of the value .

Call by value in C++ Programming language  :-

In call by value we pass the variable or say argument and then it used by function which we made so see the code given below 

Syntax -

#include <iostream >

using namespace std;

// making function 

void fun_name(int a, int b)

{

...
}

int main()

{

//calling function 

fun_name(int n,int n1);

return 0;

}

Code - 

// function call by value in C++ programming

#include <iostream>

using namespace std;

// call by value in function declaration

void container(int a, int b);

int main()

{

  int x,y;

  cout<<"Enter the value of x :"<<endl;

  cin>>x;

  cout<<"Enter the value of y :"<<endl;

  cin>>y;

  // here we passing the value as argument

  // and also calling the function

  container(x,y);

  return 0;

}

// Defining the function here

void container(int a, int b)

{

  int c , d;

  cout<<"first we found addition and subtraction"<<endl;

  cout<<"Addition of the value is :"<<endl;

  c=a+b;

  cout<<c;

  cout<<"Subtraction of the value is :"<<endl;

  d=a-b;

  cout<<d;

  cout<<"Multplication of the value we get from add & sub :"<<endl<<c*d;

}

output -

Enter the value of x :

15

Enter the value of y :

11

first we found addition and subtraction

Addition of the value is :

26Subtraction of the value is :

4Multplication of the value we get from add & sub :

104

Call by reference in C++ Programming language  -

In this we pass the address of the argument or say variable like a pointer where it will get the value and this process is called call by reference in function .

syntax - 

#include <iostream >

using namespace std;

// making function 

// You will see this * in pointer in c programming 

void fun_name(int *a, int *b)

{

...
}

int main()

{

//calling function 

fun_name(int &n,int &n1);

return 0;

}

Code -

// function call by value in C++ programming

#include <iostream>

using namespace std;

// call by value in function declaration

void container(int *a, int *b);

int main()

{

  int x,y;

  cout<<"Enter the value of x :"<<endl;

  cin>>x;

  cout<<"Enter the value of y :"<<endl;

  cin>>y;

  // here we passing the value as argument

  // and also calling the function

  container(&x,&y);

  return 0;

}

// Defining the function here

void container(int *a, int *b)

{

  int p,q;

  p=*a;

  q=*b;

  cout<<"The value which we entered is after adding :"<<endl<<p+q<<endl;

  cout<<"The value which we entered is after without use of variable : "<<endl<<*a + *b;

}

output -

     

Enter the value of x :

11

Enter the value of y :

1

The value which we entered is after adding :

12

The value which we entered is after without use of variable :

12

Why we use function ?

we use function because it help us to write a less code and making more use full of that time and we use it for more coding and it help us to make software faster in function we can pass variable and find the value what we want through function and we don't have to write code more and more time because we pass the variable thats called call by value .