Minimum difference between two elements in array

Given an array, how do we find the minimum difference between any two elements in that array?
For example consider the array [56, 18, 89, 24, 10], the minimum difference is 6 (between 18, and 24).
A straight forward method to find the minimum difference between any two pairs is to iterate through each possible pair and find the minimum difference. But this method takes O(n²) time.
This can be solved in O(n log n) time if we sort the array. Since the closest elements are always adjacent to each other in a sorted array, we can find the minimum difference in one iteration. Here is the C++ code for the same.