public member function
<forward_list>
template <class... Args>
iterator emplace_after ( const_iterator position, Args&&... args );
Construct and insert element
The container is extended by inserting a new element after the element at position. This new element is constructed in place using args as the arguments for its constructor.
This effectively increases the container size by one.
Unlike other standard sequence containers, list and forward_list objects are specifically designed to be efficient inserting and removing elements in any position, even in the middle of the sequence.
To emplace elements at the beginning of the forward_list, use member function emplace_begin, or call this function with before_begin as position.
A similar member function exists, insert_after, which either copies or moves existing objects into the container.
Parameters
- position
- Position in the container after which the new element is inserted.
Member type const_iterator is a forward iterator type.
- args
- Arguments passed to the constructor of the new element.
Return value
An iterator that points to the newly emplaced element.
Member type iterator is a forward iterator type.
The storage for the new element is allocated using allocator_traits<allocator_type>::construct(), which may throw exceptions on failure (for the default allocator, bad_alloc is thrown if the allocation request does not succeed).
Example
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
|
// forward_list::emplace_after
#include <iostream>
#include <forward_list>
int main ()
{
std::forward_list< std::pair<int,char> > mylist;
auto it = mylist.before_begin();
it = mylist.emplace_after ( it, 100, 'x' );
it = mylist.emplace_after ( it, 200, 'y' );
it = mylist.emplace_after ( it, 300, 'z' );
std::cout << "mylist contains:";
for (auto& x: mylist)
std::cout << " (" << x.first << "," << x.second << ")";
std::cout << std::endl;
return 0;
}
|
Output:
mylist contains: (100,x) (200,y) (300,z)
|
Iterator validity
All iterators, pointers and references remain valid after the insertion and refer to the same elements they were referring to before.