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std::{{{1}}}::{{{1}}}

من cppreference.com
(1)
explicit {{{1}}}( const Compare& comp = Compare(),
                  const Allocator& alloc = Allocator() );
قالب:mark since none
قالب:mark until c++14
{{{1}}}() : {{{1}}}( Compare() ) {}

explicit {{{1}}}( const Compare& comp,

                  const Allocator& alloc = Allocator() );
قالب:mark since c++14
explicit {{{1}}}( const Allocator& alloc );
(1) (since C++11)
(2)
template< class InputIt >

{{{1}}}( InputIt first, InputIt last,
         const Compare& comp = Compare(),

         const Allocator& alloc = Allocator() );
قالب:mark since none
template< class InputIt >

{{{1}}}( InputIt first, InputIt last, const Allocator& alloc)

        : {{{1}}}(first, last, Compare(), alloc) {}
قالب:mark since c++14
{{{1}}}( const {{{1}}}& other );
(3) قالب:mark since none
{{{1}}}( const {{{1}}}& other, const Allocator& alloc );
(3) (since C++11)
{{{1}}}( {{{1}}}&& other );
(4) (since C++11)
{{{1}}}( {{{1}}}&& other, const Allocator& alloc );
(4) (since C++11)
(5)
{{{1}}}( std::initializer_list<value_type> init,

         const Compare& comp = Compare(),

         const Allocator& alloc = Allocator() );
(since C++11)
{{{1}}}( std::initializer_list<value_type> init, const Allocator& alloc )
        : {{{1}}}(init, Compare(), alloc) {}
قالب:mark since c++14

Constructs new container from a variety of data sources and optionally using user supplied allocator ‎alloc‎ or comparison function object ‎comp‎.

1) Default constructor. Constructs empty container.
2) Range constructor. Constructs the container with the contents of the range ‎[first, last)‎.
3) Copy constructor. Constructs the container with the copy of the contents of ‎other‎. If ‎alloc‎ is not provided, allocator is obtained by calling std::allocator_traits<allocator_type>::select_on_container_copy_construction(other.get_allocator()).
4) Move constructor. Constructs the container with the contents of ‎other‎ using move semantics. If ‎alloc‎ is not provided, allocator is obtained by move-construction from the allocator belonging to ‎other‎.
5) Initializer-list constructor. Constructs the container with the contents of the initializer list ‎init‎.

محتويات

[تعديل] Parameters

alloc - allocator to use for all memory allocations of this container
comp - comparison function object to use for all comparisons of keys
first, last - the range to copy the elements from
other - another container to be used as source to initialize the elements of the container with
init - initializer list to initialize the elements of the container with

قالب:par hreq قالب:par req concept قالب:par req concept قالب:par req concept

[تعديل] Complexity

1) Constant

2) N log(N) where N = std::distance(first, last) in general, linear in ‎N‎ if the range is already sorted by ‎value_comp()‎.

3) Linear in size of ‎other‎

4) Constant. If ‎alloc‎ is given and alloc != other.get_allocator(), then linear.

5) N log(N) where N = init.size()) in general, linear in ‎N‎ if ‎init‎ is already sorted by ‎value_comp()‎.

[تعديل] Example

#include <iostream>
#include <string>
#include <set>
 
// Helper function for printing pairs.
template<class Ch, class Tr, class A, class B> inline
std::basic_ostream<Ch, Tr>& operator<<(std::basic_ostream<Ch, Tr>& stream, std::pair<A,B> p)
{
  return stream << '(' << p.first << ", " << p.second << ')';
}
 
// Helper function for printing containers.
template<class Ch, class Tr, class Co>
std::basic_ostream<Ch, Tr>& operator<<(std::basic_ostream<Ch, Tr>& stream, Co& c)
{
  stream << '{' << *c.begin();
 
  for(auto it = ++(c.begin()); it != c.end(); ++it)
    stream << ", " << *it;
 
  stream << '}' << std::endl;
  return stream;
}
 
int main()
{
  // (1) Default constructor
  std::set<std::string> a;
  a.insert("something");
  a.insert("anything");
  a.insert("that thing");
  std::cout << "a = " << a;
 
  // (2) Iterator constructor
  std::set<std::string> b(a.find("anything"), a.end());
  std::cout << std::string(80, '-') << std::endl;
  std::cout << "b = " << b;
 
  // (3) Copy constructor
  std::set<std::string> c(a);
  c.insert("another thing");
  std::cout << std::string(80, '-') << std::endl;
  std::cout << "a = " << a;
  std::cout << "c = " << c;
 
  // (4) Move constructor
  std::set<std::string> d(std::move(a));
  std::cout << std::string(80, '-') << std::endl;
  std::cout << "a = nullptr" << std::endl;
  std::cout << "d = " << d;
 
  // (5) Initializer list constructor
  std::set<std::string> e{
    "one", "two", "three", "five", "eight"
  };
  std::cout << std::string(80, '-') << std::endl;
  std::cout << "e = " << e;
}

الخرج:

a = {anything, something, that thing}
--------------------------------------------------------------------------------
b = {anything, something, that thing}
--------------------------------------------------------------------------------
a = {anything, something, that thing}
c = {another thing, anything, something, that thing}
--------------------------------------------------------------------------------
a = nullptr
d = {anything, something, that thing}
--------------------------------------------------------------------------------
e = {eight, five, one, three, two}

[تعديل] See also

قالب:dsc mem fun