Recursion

Triangle Numbers

The technique of expressing a solution to a problem in terms of solution to a smaller version of the same problem is called recursion.
There are two key requirements to make that recursion is successful:
- Every recursive call must simplify the computation in some way.
- The must be special case to handle the simplest computations directly.
Here, get_area calls itself again with smaller and smaller width values, eventually reaching a width of 1.

Recursion is not really necessary to solve this problem:

A simple loop:

double area = 0;
for (int i = 1; i <= width; i++)
   area = area + 1;