operator== (<iterator>)

Article
12/01/2015

Tests if the iterator object on the left side of the operator is equal to the iterator object on the right side.

Syntax

template<class RandomIterator1, class RandomIterator2>
    bool operator==(
        const move_iterator<RandomIterator1>& _Left,
        const move_iterator<RandomIterator2>& _Right
    );
template<class RandomIterator1, class RandomIterator2>
    bool operator==(
        const reverse_iterator<RandomIterator1>& _Left,
        const reverse_iterator<RandomIterator2>& _Right
   );
template<class Type, class CharType, class Traits, class Distance>
   bool operator==(
      const istream_iterator<Type, CharType, Traits, Distance>& _Left,
      const istream_iterator<Type, CharType, Traits, Distance>& _Right
   );
template<class CharType, class Tr>
   bool operator==(
      const istreambuf_iterator<CharType, Traits>& _Left,
      const istreambuf_iterator<CharType, Traits>& _Right
);

Parameters

_Left
An object of type iterator.
_Right
An object of type iterator.

Return Value

true if the iterator objects are equal; false if the iterator objects are not equal.

Remarks

One iterator object is equal to another if they address the same elements in a container. If two iterators point to different elements in a container, then they are not equal.

The first two template operators return true only if both _Left and _Right store the same iterator. The third template operator returns true only if both _Left and _Right store the same stream pointer. The fourth template operator returns _Left.equal (_Right).

Example

// iterator_op_eq.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for ( i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i );
   }

   vector <int>::iterator vIter;

   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the last element
   vector <int>::reverse_iterator rVPOS1 = vec.rbegin ( ), 
           rVPOS2 = vec.rbegin ( );

   cout << "The iterator rVPOS1 initially points to the first "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   if ( rVPOS1 == rVPOS2 )
      cout << "The iterators are equal." << endl;
   else
      cout << "The iterators are not equal." << endl;

   rVPOS1++;
   cout << "The iterator rVPOS1 now points to the second "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   if ( rVPOS1 == rVPOS2 )
      cout << "The iterators are equal." << endl;
   else
      cout << "The iterators are not equal." << endl;
}

The vector vec is: ( 2 4 6 8 10 ).
The iterator rVPOS1 initially points to the first element
 in the reversed sequence: 10.
The iterators are equal.
The iterator rVPOS1 now points to the second element
 in the reversed sequence: 8.
The iterators are not equal.

Requirements

Header: <iterator>

Namespace: std

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