The equal() function in C++ boost library is found under the header ‘boost/algorithm/cxx11/equal.hpp’ tests to see if two sequences contain equal values. It returns a boolean value which determines if both the sequences are same or not.

Syntax:

bool equal ( InputIterator1 first1, InputIterator1 second1,
                  InputIterator2 first2, InputIterator2 second2 )
or 
bool equal ( InputIterator1 first1, InputIterator1 second1,
             InputIterator2 first2, InputIterator2 second2, 
             BinaryPredicate pred )

Parameters: The function accepts parameters as described below:

• first1: It specifies the input iterators to the initial positions in the first sequence.
• second1: It specifies the input iterators to the final positions in the first sequence.
  • first2: It specifies the input iterators to the initial positions in the second sequence.
  • second2: It specifies the input iterators to the final positions in the second sequence.
  • p: It specifies the comparison predicate if specified.

  Return Value: The function returns true if both the sequence are same, else it returns false.

  Note: The above function runs for C++14 and above.

  Program-1:

  // C++ program to implement the

  // above mentioned function

  #include <bits/stdc++.h>

  #include <boost/algorithm/cxx14/equal.hpp>

  using namespace std;

  // Drivers code

  int main()

  {

  // Declares the sequences

  int a[] = { 1, 2, 5, 6, 8 };

  int b[] = { 1, 2, 5, 6, 8 };

  // Run the function

  bool ans

  = boost::algorithm::equal(a, a + 5, b, b + 5);

  // Condition to check

  if (ans == 1)

  cout << "Sequence1 and Sequence2 are equal";

  else

  cout << "Sequence1 and Sequence2 are not equal";

  return 0;

  }
  Output:

  Sequence1 and Sequence2 are equal
  

  Program-2:

  // C++ program to implement the

  // above mentioned function

  #include <bits/stdc++.h>

  #include <boost/algorithm/cxx14/equal.hpp>

  using namespace std;

  // Drivers code

  int main()

  {

  // Declares the sequences

  int a[] = { 1, 2, 5, 6, 8 };

  int b[] = { 1, 2, 5 };

  // Run the function

  bool ans

  = boost::algorithm::equal(a, a + 5, b, b + 5);

  // Condition to check

  if (ans == 1)

  cout << "Sequence1 and Sequence2 are equal";

  else

  cout << "Sequence1 and Sequence2 are not equal";

  return 0;

  }
  Output:

  Sequence1 and Sequence2 are not equal
  

  Reference: https://www.boost.org/doc/libs/1_70_0/libs/algorithm/doc/html/algorithm/CXX14.html#the_boost_algorithm_library.CXX14.equal

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