C++ Vector Library - begin() Function

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Description

The C++ function std::vector::begin() returns a random access iterator pointing to the first element of the vector.

Declaration

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

C++98

iterator begin();
const_iterator begin() const;

C++11

iterator begin() noexcept;
const_iterator begin() const noexcept;

Parameters

None

Return value

Returns a random access iterator pointing to the first element of the vector.

Exceptions

This member function never throws exception.

Time complexity

Constant i.e. O(1)

Example

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

#include <iostream>
#include <vector>

using namespace std;

int main(void) {
   auto il = {1, 2, 3, 4, 5};
   vector<int> v(il);

   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