C++ Vector Library - insert() Function

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Description

The C++ function std::vector::insert() extends vector by inserting new element at position in container. Reallocation happens if there is need of more space.

This function increases container size by one.

Declaration

Following is the declaration for std::vector::insert() function form std::vector header.

C++98

iterator insert (iterator position, const value_type& val);

C++11

iterator insert (const_iterator position, const value_type& val);

Parameters

• position − Index in the vector where new element to be inserted.

• val − Value to be assigned to newly inserted element.

Return value

Returns an iterator which points to the newly inserted element.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of std::vector::insert() function.

#include <iostream>
#include <vector>

using namespace std;

int main(void) {
   vector<int> v = {3, 4, 5};

   auto it = v.insert(v.begin(), 2);
   v.insert(it, 1);

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

   return 0;
}

Let us compile and run the above program, this will produce the following result −

1
2
3
4
5