std::equal() in C++

std::equal() helps to compares the elements within the range [first_1,last_1) with those within range beginning at first_2. Syntax 1:

template 
  bool equal (InputIterator1 first1, InputIterator1 last1,
              InputIterator2 first2)
    
first_1, last_1 : Initial and final positions of the first
    sequence. All the elements are present within a range [first_1,last_1)
first2 : Initial position of the second sequence.

Returns : 
true, if all of the elements in both ranges match; otherwise false

CPP

// C++ program illustrating
// use of  bool equal (InputIterator1 first1, InputIterator1 last1,
// InputIterator2 first2)


#include <bits/stdc++.h>

int main()
{
    int v1[] = { 10, 20, 30, 40, 50 };
    std::vector<int> vector_1 (v1, v1 + sizeof(v1) / sizeof(int) );

    // Printing vector1
    std::cout << "Vector contains : ";
    for (unsigned int i = 0; i < vector_1.size(); i++)
        std::cout << " " << vector_1[i];
    std::cout << "\n";

    // using std::equal()
    // Comparison within default constructor
    if ( std::equal (vector_1.begin(), vector_1.end(), v1) )
        std::cout << "The contents of both sequences are equal.\n";
    else
        printf("The contents of both sequences differ.");

}

Output:

Vector contains :  10, 20, 30, 40, 50
The contents of both sequences are equal.

Syntax 2:

template 
  bool equal (InputIterator1 first1, InputIterator1 last1,
              InputIterator2 first2, BinaryPredicate pred);

first_1, last_1 : Initial and final positions of the first
    sequence. All the elements are present within a range [first_1,last_1)
first2 : Initial position of the second sequence.
pred : Binary function that accepts two elements as argument 
      and returns a value convertible to boolean.

Returns : 
true, if all of the elements in both ranges match; otherwise false

CPP

// C++ program illustrating
// use of bool equal (InputIterator1 first1, InputIterator1 last1,
// InputIterator2 first2, BinaryPredicate pred);

#include <bits/stdc++.h>

bool pred(int i, int j)
{
    return (i != j);
}

int main()
{
    int v1[] = { 10, 20, 30, 40, 50 };
    std::vector<int> vector_1 (v1, v1 + sizeof(v1) / sizeof(int) );

    // Printing vector1
    std::cout << "Vector contains : ";
    for (unsigned int i = 0; i < vector_1.size(); i++)
        std::cout << " " << vector_1[i];
    std::cout << "\n";

    // using std::equal()
    // Comparison based on pred
    if ( std::equal (vector_1.begin(), vector_1.end(), v1, pred) )
        std::cout << "The contents of both sequences are equal.\n";
    else
        printf("The contents of both sequences differ.");

}

Output:

Vector contains :  10, 20, 30, 40, 50
The contents of both sequences differ.

Time complexity: O(n)

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