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std::forward_list<T,Allocator>::emplace_after

From cppreference.com
 
 
 
 
template< class... Args >
iterator emplace_after( const_iterator pos, Args&&... args );
(since C++11)

Inserts a new element into a position after the specified position in the container. The element is constructed in-place, i.e. no copy or move operations are performed. The constructor of the element is called with exactly the same arguments, as supplied to the function.

No iterators or references are invalidated.

Contents

[edit] Parameters

pos - iterator after which the new element will be constructed
args - arguments to forward to the constructor of the element

[edit] Return value

Iterator to the new element.

[edit] Complexity

Constant.

[edit] Exceptions

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

[edit] Example

The example demonstrates a canonical filling of a single-linked list in natural (as opposed to reverse) order.

#include <forward_list>
#include <iostream>
#include <string>
 
struct Sum
{
    std::string remark;
    int sum;
 
    Sum(std::string remark, int sum)
        : remark{std::move(remark)}, sum{sum} {}
 
    void print() const
    {
        std::cout << remark << " = " << sum << '\n';
    }
};
 
int main()
{
    std::forward_list<Sum> list;
 
    auto iter = list.before_begin();
    std::string str{"1"};
 
    for (int i{1}, sum{1}; i != 10; sum += i)
    {
        iter = list.emplace_after(iter, str, sum);
        ++i;
        str += " + " + std::to_string(i);
    }
 
    for (const Sum& s : list)
        s.print();
}

Output:

1 = 1
1 + 2 = 3
1 + 2 + 3 = 6
1 + 2 + 3 + 4 = 10
1 + 2 + 3 + 4 + 5 = 15
1 + 2 + 3 + 4 + 5 + 6 = 21
1 + 2 + 3 + 4 + 5 + 6 + 7 = 28
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45

[edit] See also

inserts elements after an element
(public member function) [edit]