LEC: 15

Function Parameters and Arguments

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Call by value and Call by Reference

A function parameter (sometimes called a formal parameter) is a variable declared in the function declaration:

Example :

void function(int i)

{.....}

An argument (sometimes called an actual parameter) is the value that is passed to the function by the caller:

Example :

function(17);

There are 2 ways to pass arguments to a function :

--->1. Call by value

--->2. Call by reference or Call by address

Call BY value:--

In this we Pass the copy of variable or data to the function.
The changes doesn't reflect to the original data.

Call BY Reference or call by address:--

In this we Pass the address of data to the function.
The changes reflect to the original data.

Source Code for Call By value

#include<iostream>
using namespace std;
void swap1(int a,int b) //parameters
{
int temp=a; //temp a b
a=b;
b=temp;
cout<<"Under swapping function \nthe value of a : "<<a<<" and b : "<<b<<endl;
}
int main()
{
int x=5,y=7;
cout<<"Before function call \nthe value of a : "<<x<<" and b : "<<y<<endl;
swap1(x,y); //argument
cout<<"After the function call \nthe value of a : "<<x<<" and b : "<<y<<endl;
return 0;
}

Source Code for Call By Reference

#include<iostream>
using namespace std;
void swap1(int a,int b) //parameters
{
int temp=a; //temp a b
a=b;
b=temp;
cout<<"Under swapping function \nthe value of a : "<<a<<" and b : "<<b<<endl;
}

**void swap2(int* a,int* b) //parameters
{
int temp=*a; //temp a b**
a=b;
*b=temp;
**cout<<"Under swapping function \nthe value of a : "<<a<<" and b : "<<b<<endl;
}
int main()
{
int x=5,y=7;
/*--->call by value
cout<<"Before function call \nthe value of a : "<<x<<" and b : "<<y<<endl;
swap1(x,y); //argument
cout<<"After the function call \nthe value of a : "<<x<<" and b : "<<y<<endl;**
*/
cout<<"Before function call \nthe value of a : "<<x<<" and b : "<<y<<endl;
swap2(&x,&y); //argument
cout<<"After the function call \nthe value of a : "<<x<<" and b : "<<y<<endl;
return 0;
}

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