Question

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

Short answer

Short Answer: Reference variables allow a function to access and modify the original value of a variable when used as parameters, rather than working with a separate copy of the value. This concept is known as "pass by reference." Using reference variables can be more efficient and allows functions to directly manipulate the original data in operations like sorting or updating a data structure. In C++, a reference variable is denoted with an ampersand (&) symbol, e.g., `void swap(int &a, int &b)`.

Step-by-step solution

1. Introducing Reference Variables

Reference variables allow a function to access the original argument when used as parameters. By passing a reference to a variable, any changes made to that variable within a function will also affect the original value of the variable.

2. Understanding Pass by Reference

When a variable is passed by reference, the function receives a reference to the memory location of the variable. This allows the function to directly modify the value stored at that memory location, rather than creating a separate copy of the variable's value for the function parameter.

3. Example of Pass by Reference

In C++, reference variables are denoted with an ampersand (&) symbol. Let's see an example: ```cpp #include void swap(int &a, int &b) { int temp = a; a = b; b = temp; } int main() { int x = 5; int y = 10; std::cout << "Before swap: x = " << x << ", y = " << y << std::endl; swap(x, y); std::cout << "After swap: x = " << x << ", y = " << y << std::endl; return 0; } ``` In this example, the `swap` function takes two reference variables as its parameters. When the function is called, it swaps the values of `x` and `y`, directly modifying their memory location. Thus, the output of the program will show that the values of `x` and `y` have been swapped.

4. Difference Between Pass by Reference and Pass by Value

In 'Pass by value', a copy of the variable's value is passed to the function, and any changes made to the parameter will not affect the original value of the variable. This is in contrast to 'Pass by reference', where changes made to the parameter within the function will also affect the original variable value, as the function directly works with the memory address of that variable.

5. Benefits of Using Reference Variables

There are several benefits to using reference variables: 1. They allow you to directly modify the original value of a variable, which can be useful for certain operations, such as sorting or updating a data structure. 2. Passing by reference can be more efficient in some cases, as it avoids the need to create a separate copy of the variable for the function parameter. 3. Reference variables can also be used to return multiple values from a function without using extra data structures.