std::list::merge

 

C++

Language

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

 

std::list

Member functions

list::list

list::~list

list::operator=

list::assign

list::get_allocator

Element access

list::front

list::back

Iterators

list::begin list::cbegin (C++11)

list::end list::cend (C++11)

list::rbegin list::crbegin (C++11)

list::rend list::crend (C++11)

Capacity

list::empty

list::size

list::max_size

Modifiers

list::clear

list::insert

list::emplace (C++11)

list::erase

list::push_front

list::emplace_front (C++11)

list::pop_front

list::push_back

list::emplace_back (C++11)

list::pop_back

list::resize

list::swap

Operations

list::merge

list::splice

list::remove list::remove_if

list::reverse

list::unique

list::sort

 

void merge( list& other );	(1)
void merge( list&& other );	(1)	(since C++11)
template <class Compare> void merge( list& other, Compare comp );	(2)
template <class Compare> void merge( list&& other, Compare comp );	(2)	(since C++11)

Merges two sorted lists into one. The lists should be sorted into ascending order.

No elements are copied. The container other becomes empty after the operation. The function does nothing if this == &other. If get_allocator() != other.get_allocator(), the behavior is undefined. No iterators or references become invalidated, except that the iterators of moved elements now refer into *this, not into other. The first version uses operator< to compare the elements, the second version uses the given comparison function comp.

Parameters

other	-	another container to merge
comp	-	comparison function which returns ​true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following: bool cmp(const Type1 &a, const Type2 &b); The signature does not need to have const &, but the function must not modify the objects passed to it. The types  Type1 and  Type2 must be such that an object of type list<T,Allocator>::const_iterator can be dereferenced and then implicitly converted to both of them. ​

Return value

(none)

Example

#include <iostream>
#include <list>
 
std::ostream& operator<<(std::ostream& ostr, const std::list<int>& list)
{
    for (auto &i : list) {
        ostr << " " << i;
    }
    return ostr;
}
 
int main()
{
    std::list<int> list1 = { 5,9,0,1,3 };
    std::list<int> list2 = { 8,7,2,6,4 };
 
    list1.sort();
    list2.sort();
    std::cout << "list1:  " << list1 << "\n";
    std::cout << "list2:  " << list2 << "\n";
    list1.merge(list2);
    std::cout << "merged: " << list1 << "\n";
}

Output:

list1:   0 1 3 5 9
list2:   2 4 6 7 8
merged:  0 1 2 3 4 5 6 7 8 9

Complexity

at most size() + other.size() - 1 comparisons.

See also

splice	moves elements from another list (public member function)