[praptak]

The original application of the sentinel technique makes linear search faster.

Looking for 42 in a table of integers? Put 42 after the last element (obviously you need n+1 elements allocated) and your loop does not need to check array bounds, only checking for a[i]==42 is now guaranteed to stop and not read past the array bounds.

(obviously it doesn't work if multiple threads search the same table for different values)