std::forward_list emplace_after() method

since C++11

// Non const version only
template< class... Args >
iterator emplace_after( const_iterator pos, Args&&... args );

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.

Parameters

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

Return value

Iterator pointing to the new element.

Complexity

Constant - O(1).

Exceptions

If an exception is thrown by any operation, the are no effect (strong exception guarantee).

Example

Main.cpp

#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