Man Page equal.3

                       Standard C++ Library
             Copyright 1998, 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  ele-
     ments  available  after  first2  as  there  are in the range
     [first1, last1).

COMPLEXITY

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

EXAMPLE

     //
     // equal.cpp
     //
      #include <algorithm>
      #include <vector>
      #include <functional>
      #include <iostream>
     using namespace std;

     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;
      }

     Program Output
     FALSE FALSE

WARNINGS

     If your compiler does not support default  template  parame-
     ters,  then you always need to supply the Allocator template
     argument. For instance, you have to write:

     vector<int,allocator<int> >

     instead of:

     vector<int>

     If your compiler does not support namespaces,  then  you  do
     not need the using declaration for std.