W3cubDocs

/C++

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

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 (e.g. by the constructor), the container is left unmodified, as if this function was never called (strong exception guarantee).

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: