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

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C++
Containers library
std::forward_list
Member functions
Non-member functions
(until C++20) (until C++20) (until C++20) (until C++20) (until C++20)
Deduction guides (C++17)
iterator insert_after ( const_iterator pos, const T & value ) ;
(1) (since C++11)
(constexpr since C++26)
iterator insert_after ( const_iterator pos, T && value ) ;
(2) (since C++11)
(constexpr since C++26)
iterator insert_after ( const_iterator pos,
size_type count, const T & value ) ;
(3) (since C++11)
(constexpr since C++26)
template < class InputIt >

iterator insert_after ( const_iterator pos,

InputIt first, InputIt last ) ;
(4) (since C++11)
(constexpr since C++26)
iterator insert_after ( const_iterator pos,
std:: initializer_list < T > ilist ) ;
(5) (since C++11)
(constexpr since C++26)

Inserts elements after the specified position in the container. If pos is before_begin() , the first element inserted (if exists) will become the first element of * this .

If pos is not in the range [ before_begin() , end() ) , the behavior is undefined.

1,2) Inserts a copy of value after pos .
1) If T is not CopyInsertable into forward_list , the behavior is undefined.
2) If T is not MoveInsertable into forward_list , the behavior is undefined.
3) Inserts count copies of the value after pos .
If T is not CopyInsertable into forward_list , the behavior is undefined.
4) Inserts elements from range [ first , last ) after pos .
This overload participates in overload resolution only if InputIt satisfies the requirements of LegacyInputIterator .
If any of the following conditions is satisfied, the behavior is undefined:
5) Inserts elements from initializer list ilist after pos .
Equivalent to return insert_after ( position, ilist. begin ( ) , ilist. end ( ) ) ; .

No iterators or references are invalidated.

Contents

Parameters

pos - iterator after which the content will be inserted
value - element value to insert
count - number of copies to insert
first, last - the pair of iterators defining the source range of elements to insert
ilist - initializer list to insert the values from

Return value

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

constructs elements in-place after an element
(public member function)
inserts an element to the beginning
(public member function)