Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.

NAME

  equal  - Compares two ranges for equality.

SYNOPSIS

  #include <algorithm>

  template <class InputIterator1, class InputIterator2>
  bool equal(InputIterator1 first1, InputIterator1 last1,
             InputIterator2 first2);

  template <class InputIterator1, class InputIterator2,
           class BinaryPredicate>
  bool equal(InputIterator1 first1, InputIterator1 last1,
             InputIterator2 first2, BinaryPredicate binary_pred);

DESCRIPTION

  The equal algorithm does a pairwise comparison of all of the elements in
  one range with all of the elements in another range to see if they match.
  The first version of equal uses the equal operator (==) as the comparison
  function, and the second version allows you to specify a binary predicate
  as the comparison function. The first version returns true if all of the
  corresponding elements are equal to each other.  The second version of
  equal returns true if for each pair of elements in the two ranges, the
  result of applying the binary predicate is true.  In other words, equal
  returns true if both of the following are true:

  1. There are at least as many elements in the second range as in the first;

  2. For every iterator i in the range [first1, last1) the following
       corresponding conditions hold:

     *i == *(first2 + (i - first1))

         or

    binary_pred(*i, *(first2 + (i - first1))) == true

  Otherwise, equal returns false.

  This algorithm assumes that there are at least as many elements available
  after first2 as there are in the range [first1, last1).

COMPLEXITY

  equal performs at most last1-first1 comparisons or applications of the
  predicate.

EXAMPLE

  //
  // equal.cpp
  //
   #include <algorithm>
   #include <vector>
   #include <iostream.h>

  int main()
   {
    int d1[4] = {1,2,3,4};
    int d2[4] = {1,2,4,3};
     //
     // Set up two vectors
     //
    vector<int> v1(d1+0, d1 + 4), v2(d2+0, d2 + 4);

     // Check for equality
    bool b1 = equal(v1.begin(),v1.end(),v2.begin());
    bool b2 = equal(v1.begin(),v1.end(),
                    v2.begin(),equal_to<int>());

     // Both b1 and b2 are false
    cout << (b1 ? "TRUE" : "FALSE")  << " "
          << (b2 ? "TRUE" : "FALSE") << endl;
    return 0;
   }

  Output :
  FALSE FALSE

WARNINGS

  If your compiler does not support default template parameters then you need
  to always supply the Allocator template argument.  For instance you'll have
  to write:

  vector<int,allocator<int> >

  instead of:

  vector<int>

STANDARDS CONFORMANCE

  ANSI X3J16/ISO WG21 Joint C++ Committee



privacy and legal statement