Vectors are similar to dynamic arrays in that they may resize themselves dynamically when an element is added or removed, and their storage is handled automatically by the container.


 vector Declaration


#include <iostream>
#include <bits/stdc++.h>
using namespace std;
int main()
{
    vector<int> v;  /// vector1 declatation
 
    vector<int> v2;  /// vector2 declatation
 

 push_back()

It push the elements into a vector from the back

int main()
{
    vector<int> v;   /// vector1 declaration
    v.push_back(1); // value input
    v.push_back(2);
    v.push_back(3);
    v.push_back(4);
    v.push_back(5);

    vector<int> v2; /// vector2 declaration
    v2.push_back(11);  
    v2.push_back(12);  
    v2.push_back(13);  
    v2.push_back(14);

 

Print a vector 

Type 1:-

 
vector<int>::iterator it; // iterator declaration

    for (it = v.begin(); it != v.end(); it++)
    {
         cout << *it << " ";
     }


Type 2:-


// auto iterator ///
    for (int i = 0; i < v.size(); i++)
    {
         cout << v[i] << " ";
    }


 front()


cout <<"Front : "<< v.front() << endl;


 back()


cout <<"Back  :"<< v.back() << endl;

for (int i = 0; i < v.size(); i++)
{
         cout << v[i] << " ";// print vecter
}


 pop_back()

v.pop_back() ;

for (int i = 0; i < v.size(); i++)
{
         cout << v[i] << " ";
}

size()

  cout << "size : " << v.size() << endl;

 clear()

v.clear();
for (int i = 0; i < v.size(); i++)
{
         cout << v[i] << " ";
}

 empty()

 cout <<"empty : "<< v.empty() << endl;
// if empty ==0 then true else empty==1 false

 

insert()

 
v.insert(v.begin()+5,99);///  insert index and input number


 erase()

 
v.erase(v.begin()+5 );/// erase by index number


 reverse()


   reverse(v.begin(),v.end()); // first index
   reverse(v.begin()+4,v.end()); //with index number

for (int i = 0; i < v.size(); i++)
{
         cout << v[i] << " ";// print vecter
}


sort()


  sort(v.begin(),v.end()); // first index
   
     sort(v.begin()+4,v.end());// input index number

for (int i = 0; i < v.size(); i++)
{
         cout << v[i] << " ";// print vecter
}

 

swap()


swap(v, v2); /// swap between 2 vectors
for (int i = 0; i < v.size(); i++)
{
         cout << v[i] << " ";// print vecter
}