C++ Vector Library - vector() Function

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Description

The C++ range constructor std::vector::vector() constructs a container with as many elements in range of first to last.

Assigns value to container elements in range of [first, last].

Declaration

Following is the declaration for range constructor std::vector::vector() form std::vector header.

C++98

template <class InputIterator> vector (InputIterator first, InputIterator last, 
   const allocator_type& alloc = allocator_type());

C++11

template <class InputIterator> vector (InputIterator first, InputIterator last,
   const allocator_type& alloc = allocator_type());

Parameters

• first − Input iterator to the initial position in range.

• last − Input itertor to the final position in range.

Return value

Constructor never returns value.

Exceptions

This member function never throws exception.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of range constructor std::vector::vector().

#include <iostream>
#include <vector>

using namespace std;

int main(void) {
   vector<int> v1(5);

   /* assigned value to vector v1 */
   for (int i = 0; i < v1.size(); ++i)
      v1[i] = i + 1;

   /* create a range constructor v2 from v1 */
   vector<int> v2(v1.begin(), v1.end());

   for (int i = 0; i < v2.size(); ++i)
      cout << v2[i] << endl;

   return 0;
}

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

1
2
3
4
5