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

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< cpp‎ | container‎ | forward list

iterator insert_after( const_iterator pos, const T& value ); | (1) | (since C++11)
iterator insert_after( const_iterator pos, T&& value ); | (2) | (since C++11)
iterator insert_after( const_iterator pos, size_type count, const T& value ); | (3) | (since C++11)
template< class InputIt > iterator insert_after( const_iterator pos, InputIt first, InputIt last ); | (4) | (since C++11)
iterator insert_after( const_iterator pos, std::initializer_list<T> ilist ); | (5) | (since C++11)

Inserts elements after the specified position in the container.

1-2) inserts value after the element pointed to by pos
3) inserts count copies of the value after the element pointed to by pos
4) inserts elements from range `[`first`,` last`)` after the element pointed to by pos. The behavior is undefined if first and last are iterators into *this.
5) inserts elements from initializer list ilist.

No iterators or references are invalidated.

### Parameters

pos | - | iterator after which the content will be inserted
value | - | element value to insert
count | - | number of copies to insert
first, last | - | the range of elements to insert
ilist | - | initializer list to insert the values from
Type requirements
- `InputIt` must meet the requirements of LegacyInputIterator.

### Return value

1-2) Iterator to the inserted element.
3) Iterator to the last element inserted, or pos if count==0.
4) Iterator to the last element inserted, or pos if first==last.
5) Iterator to the last element inserted, or pos if ilist is empty.

### Exceptions

If an exception is thrown for any reason, these functions have no effect (strong exception safety guarantee).

### Complexity

1-2) Constant.
3) Linear in count
4) Linear in std::distance(first, last)
5) Linear in ilist.size()

### Example

Run this code

    #include <forward_list>
    #include <iostream>
    #include <string>
    #include <vector>

    void print(const std::forward_list<int>& list)
    {
        std::cout << "list: {";
        for (char comma[3] = {'\0', ' ', '\0'}; int i : list)
        {
            std::cout << comma << i;
            comma[0] = ',';
        }
        std::cout << "}\n";
    }

    int main()
    {
        std::forward_list<int> ints {1, 2, 3, 4, 5};
        print(ints);

        // insert_after (2)
        auto beginIt = ints.begin();
        ints.insert_after(beginIt, -6);
        print(ints);

        // insert_after (3)
        auto anotherIt = beginIt;
        ++anotherIt;
        anotherIt = ints.insert_after(anotherIt, 2, -7);
        print(ints);

        // insert_after (4)
        const std::vector<int> v = {-8, -9, -10};
        anotherIt = ints.insert_after(anotherIt, v.cbegin(), v.cend());
        print(ints);

        // insert_after (5)
        ints.insert_after(anotherIt, {-11, -12, -13, -14});
        print(ints);
    }

Output:

    list: {1, 2, 3, 4, 5}
    list: {1, -6, 2, 3, 4, 5}
    list: {1, -6, -7, -7, 2, 3, 4, 5}
    list: {1, -6, -7, -7, -8, -9, -10, 2, 3, 4, 5}
    list: {1, -6, -7, -7, -8, -9, -10, -11, -12, -13, -14, 2, 3, 4, 5}

### See also

emplace_after (C++11) | constructs elements in-place after an element (public member function)
push_front (C++11) | inserts an element to the beginning (public member function)

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