To find the median value in an array, you must first sort it so that
its values are in increasing or decreasing order.

Once that is done, you select the middle element. If the array has 7 
items, its middle element is the 4th element. In a C array, the 4th 
element has subscript 3. How do you get this subscript - try dividing the 
number of elements (7) by 2.

If the array has an even number of elements, you need to average the two 
elements in the middle. If the array has 6 elmements, you need to average 
the elements with subscripts 2 and 3. How do you get these two subscripts?
One you get by dividing the number of elements by 2. You should be able 
to figure out how to get the other one - the difference between the two 
subscripts is 1.

Now how do you now whether the array has an odd number or an even number 
of elements? You can test the remainder of the number of elements divided 
by 2 (num % 2). If the remainder is 0, num is even.