template<class FwdIt, class T>
FwdIt remove(FwdIt first, FwdIt last, const T& val);
The template function effectively assigns first to X, then executes the statement:
if (!(*(first + N) == val))
*X++ = *(first + N);
once for each N in the range [0, last - first). Here, operator== must impose an equivalence relationship between its operands. It then returns X. Thus, the function removes from the sequence all elements for which the predicate *(first + N) == val is true, without altering the relative order of remaining elements, and returns the iterator value that designates the end of the revised sequence.