Essential C++

set_difference()

set_difference() constructs a sorted sequence of the elements present in a first sequence but not present in a second. For example, given the two sequences {0,1,2,3} and {0,2,4,6}, the set difference is {1,3}. All the set algorithms (three additional algorithms follow) take five iterators: The first two mark the first sequence, and the second two mark the second sequence. The fifth iterator marks the position of the container into which to copy the elements. The algorithm presumes that the sequences are sorted using the less-than operator; an optional sixth argument allows us to pass in an alternative ordering operation.