std::string::remove_copy(), std::string::remove_copy_if() in C++

remove_copy()

• The resulting range is shorter than [first,last) by as many elements as matches in the sequence, which are "removed".
• The relative order of the elements not removed is preserved.
• The function uses operator == to compare the individual elements to given value.

ResultIterator remove_copy(ForwardIterator first, ForwardIterator last, 
ResultIterator result ,const T& ele);

first, last :  Forward iterators to the initial and final positions
in a sequence. The range used is [first, last), which contains all the elements
between first and last, including the element pointed by first but not 
the element pointed by last.

result : Output iterator to the initial position of the range 
where the resulting sequence is stored. The pointed type shall support being 
assigned the value of an element in the range [first, last).

ele : element to be removed.

Input : b d a f g h a k given element is a
Output :b d f g h k _ _ 
Input : b k c s n m c l given element is c
Output : b k s n m l _ _

'_' represent remove places

elements of v1 before remove_copy: 
4 5 0 1 2 3 4 5 0 1 2 3 4 5 0 1 
After removing element 3
4 5 0 1 2 4 5 0 1 2 4 5 0 1 0 1

remove_copy_if

• Copies the elements in the range [first, last) to the range beginning at result, except those elements for which condition function returns true.
• The resulting range is shorter than [first, last) by as many elements as matches, which are "removed".

ResultIterator remove_copy_if(ForwardIterator first, ForwardIterator last,
 ResultIterator result, UnaryPredicate pred);
pred :  Unary function that accepts an element in the range as
argument, and returns a value convertible to bool. The value returned indicates
 whether the element is to be removed (if true, it is removed).

Input : 1 2 3 4 5 6 7 8 9 check if a number is prime and remove
Output :1 4 6 8 9 0 0 0 0

Input :1 2 3 4 5 6 7 8 9 check if a number is even and remove
Output :1 3 5 7 9 0 0 0 0