# 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> >

vector<int>

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

```