Detailed explanation of the usage example of C++ set

template < class T, // set::key_type/value_type
            class Compare = less<T>, // set::key_compare/value_compare
            class Alloc = allocator<T> // set::allocator_type
            > class set;

// empty (1) Default construct without parametersexplicit set (const key_compare& comp = key_compare(),
const allocator_type& alloc = allocator_type());
// range (2) Iterator interval constructiontemplate <class InputIterator>
set (InputIterator first, InputIterator last,
const key_compare& comp = key_compare(),
const allocator_type& = allocator_type());
// copy (3) copy constructset (const set& x);
// initializer list (5) initializer list constructionset (initializer_list<value_type> il,
const key_compare& comp = key_compare(),
const allocator_type& alloc = allocator_type());
// Iterator is a bidirectional iteratoriterator -> a bidirectional iterator to const value_type
// Forward iteratoriterator begin();
iterator end();
// Reverse iteratorreverse_iterator rbegin();
reverse_iterator rend();

Member types
key_type -> The first template parameter (T)
value_type -> The first template parameter (T)
// Insert a single data, if it already exists, the insertion failspair<iterator,bool> insert (const value_type& val);
// List insertion, values ​​that already exist in the container will not be insertedvoid insert (initializer_list<value_type> il);
// Iterator interval is inserted, and values ​​that already exist in the container will not be insertedtemplate <class InputIterator>
void insert (InputIterator first, InputIterator last);
// Find val, return the iterator where val is located, and return end() is not founditerator find (const value_type& val);
// Find val and return the number of Valsize_type count (const value_type& val) const;
// Delete the value of the position of an iteratoriterator erase (const_iterator position);
// Delete val, val does not exist and returns 0, and returns 1 if it existssize_type erase (const value_type& val);
// Delete the value of an iterator intervaliterator erase (const_iterator first, const_iterator last);
// Return an iterator greater than or equal val positioniterator lower_bound (const value_type& val) const;
// Returns an iterator greater than the val positioniterator upper_bound (const value_type& val) const;

#include<iostream>
#include<set>
using namespace std;
int main()
{
    // Deduplication + ascending order    set<int> s;
    // Deduplication + descending order sort (give a functor greater than)    //set<int, greater<int>> s;
    (5);
    (2);
    (7);
    (5);
    //set<int>::iterator it = ();
    auto it = ();
    while (it != ())
    {
        // error C3892: "it": Cannot assign values ​​to constants        // *it = 1;
        cout << *it << " ";
        ++it;
    }
    cout << endl;
    // Insert an initializer_list list value, the existing value failed to be inserted    ({ 2,8,3,9 });
    for (auto e : s)
    {
        cout << e << " ";
    }
    cout << endl;
    set<string> strset = { "sort", "insert", "add" };
    // traversal string compares ascll code size traversal    for (auto& e : strset)
    {
        cout << e << " ";
    }
    cout << endl;
}

#include<iostream>
#include<set>
using namespace std;
int main()
{
    set<int> s = { 4,2,7,2,8,5,9 };
    for (auto e : s)
    {
        cout << e << " ";
    }
    cout << endl;
    // Delete the minimum value    (());
    for (auto e : s)
    {
        cout << e << " ";
    }
    cout << endl;
    // Delete x directly    int x;
    cin >> x;
    int num = (x);
    if (num == 0)
    {
        cout << x << "Not exists!" << endl;
    }
    for (auto e : s)
    {
        cout << e << " ";
    }
    cout << endl;
    // Directly search and delete x using iterator    cin >> x;
    auto pos = (x);
    if (pos != ())
    {
        (pos);
    }
    else
    {
        cout << x << "Not exists!" << endl;
    }
    for (auto e : s)
    {
        cout << e << " ";
    }
    cout << endl;
    // Finding of algorithm library O(N)    auto pos1 = find((), (), x);
    // Set's own implementation of search O(logN)    auto pos2 = (x);
    // Use count to indirectly realize quick search    cin >> x;
    if ((x))
    {
        cout << x << "exist!" << endl;
    }
    else
    {
        cout << x << "Not exists!" << endl;
    }
    return 0;
}

#include<iostream>
#include<set>
using namespace std;
int main()
{
    std::set<int> myset;
    for (int i = 1; i < 10; i++)
    (i * 10); // 10 20 30 40 50 60 70 80 90
    for (auto e : myset)
    {
        cout << e << " ";
    }
    cout << endl;
    // The [itlow,itup) found in the implementation contains the [30, 60] interval    // Return >= 30    auto itlow = myset.lower_bound(30);
    // Return > 60    auto itup = myset.upper_bound(60);
    // Delete the value of this interval    (itlow, itup);
    for (auto e : myset)
    {
        cout << e << " ";
    }
    cout << endl;
    return 0;
}

#include<iostream>
#include<set>
using namespace std;
int main()
{
    // What's different from set is that multiset is sorting, but does not repetition    multiset<int> s = { 4,2,7,2,4,8,4,5,4,9 };
    auto it = ();
    while (it != ())
    {
        cout << *it << " ";
        ++it;
    }
    cout << endl;
    // Compared to set, there may be multiple x, find to find the first in the order    int x;
    cin >> x;
    auto pos = (x);
    while (pos != () && *pos == x)
    {
        cout << *pos << " ";
        ++pos;
    }
    cout << endl;
    // What's different from set is that count will return the actual number of x    cout << (x) << endl;
    // What's different from set is that when erase gives value, all x will be deleted    (x);
    for (auto e : s)
    {
        cout << e << " ";
    }
    cout << endl;
    return 0;
}