C++ set insert() Function

C++ set insert() Function with tutorial for beginners and professionals with examples on constructor, destructor, operator=(), begin(), cbegin(), cend(), end(), crbegin(), empty(), max_size(), clear(), emplace_hint(), key_comp(), swap() etc.

<< Back to CPP

next → ← prev

C++ set insert()

C++ set insert() is used for inserting new element in the set.

Because element keys are unique in a set, the insertion operation first checks that whether the given key is already present in the set or not, if the key is present in the set then it is not inserted in the set and the iterator to the existing key is returned otherwise new element is inserted in the set.

Syntax

single element (1)     pair<iterator,bool> insert (const value_type& val);   //until C++ 11

with hint (2)	iterator insert (iterator position, const value_type& val);   //until C++ 11

range (3)	  template <class InputIterator>
  		   void insert (InputIterator first, InputIterator last);        //until C++ 11

single element (1)  pair<iterator,bool> insert (const value_type& val);
                                pair<iterator,bool> insert (value_type&& val);           //since C++ 11
            
with hint (2)	iterator insert (const_iterator position, const value_type& val);
                          iterator insert (const_iterator position, value_type&& val); //since C++ 11

range (3)	template <class InputIterator>
                          void insert (InputIterator first, InputIterator last);            //since C++ 11

initializer list (4)       void insert (initializer_list<value_type> il);              //since C++ 11

Parameter

val: value to insert in the set.

position: Hint for the position to insert element in the set.

first: Beginning of range to insert.

last: End of range to insert.

il: An initializer list.

Return value

Returns a bool pair to indicate whether insertion is happened or not and returns an iterator pointing to the newly inserted element.

Complexity

If a single element is inserted complexity will be logarithmic in size.
If a hint is given and the position given is the optimal then the complexity will be amortized constant.

Iterator validity

No changes.

Data Races

The container is modified.

Exception Safety

This function does not throw exception.

Example 1

Let's see the simple example to insert the elements into the set:

#include <iostream>
#include <set>

using namespace std;
int main()
{
    set<int> s;
 
    // Function to insert elements
    // in the set container
    s.insert(1);
    s.insert(4);
    s.insert(2);
    s.insert(5);
    s.insert(3);
 
    cout << "The elements in set are: ";
    for (auto it = s.begin(); it != s.end(); it++)
        cout << *it << " ";
 
    return 0;
}

Output:

The elements in set are: 1 2 3 4 5

In the above example, it simply inserts the element with the given key.

Example 2

Let's see a simple example to insert the element in the specified position:

#include <iostream>
#include <set>

using namespace std;

int main()
{ 
    set<int> s;
 
    // Function to insert elements
    // in the set container
    auto itr = s.insert(s.begin(), 1);
 
    // the time taken to insertion
    // is very less as the correct
    // position for insertion is given
    itr = s.insert(itr, 4);
    itr = s.insert(itr, 2);
    itr = s.insert(itr, 5);
    itr = s.insert(itr, 3);
 
    cout << "The elements in set are: ";
    for (auto it = s.begin(); it != s.end(); it++)
        cout << *it << " ";
 
    return 0;
}

Output:

The elements in set are: 1 2 3 4 5

In the above example, elements are inserted in the defined position.

Example 3

Let's see a simple example to insert the elements of one set to another in a given range:

#include <iostream>
# include<iostream>
# include<set>

using namespace std;

int main()
{ 
    set<int> s1;
 
    // Function to insert elements
    // in the set container
    s1.insert(1);
    s1.insert(4);
    s1.insert(2);
    s1.insert(5);
    s1.insert(3);
 
    cout << "The elements in set1 are: ";
    for (auto it = s1.begin(); it != s1.end(); it++)
        cout << *it << " ";
 
    set<int> s2;
 
    // Function to insert one set to another
    // all elements from where 3 is to end is
    // inserted to set2
    s2.insert(s1.find(3), s1.end());
 
    cout << "\nThe elements in set2 are: ";
    for (auto it = s2.begin(); it != s2.end(); it++)
        cout << *it << " ";
 
    return 0;
}

Output:

The elements in set1 are: 1 2 3 4 5 
The elements in set2 are: 3 4 5

Example 4

Let's see a simple example to insert the elements from the initializer list:

#include <iostream>
#include <set>

using namespace std;

int main(void) {
   set<string> m = {"Java", "C++", "SQL"};
   
  // Insert the elements from an initializer_list 
   m.insert({"VB", "Oracle"});

   cout << "Set contains following elements" << endl;

   for (auto it = m.begin(); it != m.end(); ++it)
      cout << *it<< endl;

   return 0;
}

Output:

Set contains following elements
C++
Java
Oracle
SQL
VB

In the above example, elements are inserted from an initializer list.

Next TopicSet erase() Function

← prev next →

.Net

.NET Array Dictionary List String 2D Async DataTable Dates DateTime Enum File For Foreach Format IEnumerable If IndexOf Lambda LINQ Parse Path Process Property Regex Replace Sort Split Static StringBuilder Substring Switch Tuple

Java

Core Array ArrayList HashMap String 2D Cast Character Console Deque Duplicates File For Format HashSet If IndexOf Lambda Math ParseInt Process Random Regex Replace Sort Split StringBuilder Substring Switch Vector While

TheDeveloperBlog.com

C++ set insert() Function

C++ set insert()

Syntax

Parameter

Return value

Complexity

Iterator validity

Data Races

Exception Safety

Example 1

Example 2

Example 3

Example 4

Related Links:

.Net

Java

Related Links