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

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< cpp‎ | container‎ | forward list

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.

### Parameters

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

### Return value

iterator to the new element.

### Complexity

Constant.

### Exceptions

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

### Example

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

Run this code

    #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

### See also

insert_after (C++11) | inserts elements after an element (public member function)

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