When used as parameters, variables allow a function to access the parameter’s
original argument.

 reference

Explanation:

In an function if the variables are passed as reference variables this means that the variables are pointing to the original arguments.So the changes made in the function on the reference variables will be reflected back on the original arguments.

For example:-

#include<iostream>

using namespace std;

void swap(&int f,&int s)

{

    int t=f;

    f=s;

   s =temp;

}

int main()

{

int n,m;

n=45;

m=85;

swap(n,m);

cout<<n<<" "<<m;

return 0;

}

the values of m and n will get swapped.

#include<iostream>

using namespace std;

void swapv(int f,int s)

{

    int t=f;

    f=s;

    s=temp;

}

int main()

{

int n,m;

n=45;

m=85;

swapv(n,m);

cout<<n<<" "<<m;

return 0;

}

In this program the values of m and n will not get swapped because they are passed by value.So duplicate copies of m and n will be created and manipulation will be done on them.

answer; (& & );