vectorSTL

#include<bits/stdc++.h>
using namespace std;
int main()
{
        vector<int>v(5,5);//a vector with n elements and all equal to 5;
        for(int i=0 ; i < 5; i++)
               v.push_back(i+1);
        //PRINT VECTOR
        vector<int>::iterator it;
        for(it=v.begin();it!=v.end();it++)
                cout<<*it<<" ";
        for(auto it:v)
                cout<<it<<" ";
        for(auto it=v.begin();it!=v.end();it++)
                cout<<*it<<" ";
        vector<int>::reverse_iterator itr;
        for(itr=v.rbegin();itr!=v.rend();itr++)
                cout<<*itr<<" ";
        for(auto itr=v.rbegin();itr!=v.rend();itr++)
                cout<<*itr<<" "*/

        //REVERSE PRINT VECTOR

         vector<int>::iterator it1=v.end();
         it1--;
         for(;it1>=v.begin();it1--)
                cout<<*it1<<" ";

         while(it1!=v.begin()){
                it1--;
         cout<<*it1<<" ";
         }


         if(v.empty())
                cout<<"vector is empty"<<" "<<v.empty();//value of v.empty()=1;
        else
                cout<<"not empty"<<v.empty()<<" ";//value of v.empty()=0;

        cout<<v.front()<<" "; //first element of vector
        cout << v.back() << " "; //last element of vector
        cout << v.at(4) << " "; //vector at index i

        v.clear(); //to clear the vector;

        //INSERT FUNCTION
        v.insert(iterator,5);//inset 5 at the iterator position  iterator =v.begin();
        v.insert(it, 2, 4); //// inserts 4 two times at iterator position ;
        v.insert(position, iterator1 , iterator2) //

        //ERASE FUNCTION;
        v.erase(it); //removes the element at the iterator position ;
        v.erase(it1,it2)//removes the elements from it1 to it2(!=it2);

        v.swap(v2);//swap v1 and v2;

        //SORT
        sort(v.begin(),v.end()); //sort in ascend. order;
        sort(v.rbegin(),v.rend()); //sort in descend order;
                return 0;
}