equal (3C++std) - Tru64 UNIX
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
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