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

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< cpp‎ | container‎ | forward list

template< container-compatible-range<T> R > iterator insert_range_after( const_iterator pos, R&& rg ); |  | (since C++23)

Inserts, in non-reversing order, the copies of elements in rg before pos. Each iterator in the range rg is dereferenced exactly once.

pos must be any dereferenceable iterator in the range `[`begin()`,` end()`)` or the before_begin() iterator (thus, end() is not a valid argument for pos).

No iterators or references become invalidated.

The behavior is undefined if rg overlaps with the container.

### Parameters

pos | - | an iterator after which the content will be inserted.
rg | - | a container compatible range, that is, an `input_range` whose elements are convertible to `T`.
Type requirements
- `T` must be EmplaceConstructible into `forward_list` from *ranges::begin(rg). Otherwise, the behavior is undefined.

### Return value

An `iterator` that points at the copy of the last element inserted into `forward_list` or at pos if rg is empty.

### Complexity

Linear in size of rg.

### Notes

Feature-test macro | Value | Std | Comment
--- | --- | --- | ---
`__cpp_lib_containers_ranges` | 202202L | (C++23) | Ranges-aware construction and insertion

### Example

Run this code

    #include <algorithm>
    #include <cassert>
    #include <forward_list>
    #include <iterator>

    int main()
    {
        auto data = std::forward_list{1, 2, 3, 4};
        auto pos = std::next(data.cbegin());
        assert(*pos == 2);
        const auto infix = {-1, -2, -3};

    #ifdef __cpp_lib_containers_ranges
        data.insert_range_after(pos, infix);
    #else
        data.insert_after(pos, infix.begin(), infix.end());
    #endif

        assert(std::ranges::equal(data, std::forward_list{1, 2, -1, -2, -3, 3, 4}));
    }

### See also

prepend_range (C++23) | adds a range of elements to the beginning (public member function)
insert_after (C++11) | inserts elements after an element (public member function)
emplace_after (C++11) | constructs elements in-place after an element (public member function)

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