What is meant by reference variable in C++?

What is meant by reference variable in C++?

In C++, reference variable allows you create an alias (second name) for an already existing variable. A reference variable can be used to access (read/write) the original data. That means, both the variable and reference variable are attached to same memory location. In effect, if you change the value of a variable using reference variable, both will get changed (because both are attached to same memory location).

How to create a reference variable in C++
Appending an ampersand (&) to the end of datatype makes a variable eligible to use as reference variable.

int a = 20;
int& b = a;
   

The first statement initializes a an integer variable a. Second statement creates an integer reference initialized to variable a
Take a look at the below example to see how reference variables work.

int main ()
{
 int   a;
 int&  b = a;
 
 a = 10;
 cout << "Value of a : " << a << endl;
 cout << "Value of a reference (b) : " << b  << endl;
 
 b = 20;
 cout << "Value of a : " << a << endl;
 cout << "Value of a reference (b) : " << b  << endl;
 
 return 0;
}

Above code creates following output.

Value of a : 10
Value of a reference (b) : 10
Value of a : 20
Value of a reference (b) : 20