Relational Operators on STL Array in C++

The article illustrates the working of the different relational operator on the array STL. The equality comparison ( == ) is performed by comparing the elements sequentially using operator ( == ), stopping at the first mismatch.
The less-than comparison ( < ) or greater-than comparison ( > ) behaves as if using algorithm lexicographical_compare, which compares the elements sequentially using operator () in a reciprocal manner (i.e., checking both a<b and b<a) and stopping at the first occurrence.
The implementation of relational operators on the array help us to compare between the data stored in different arrays.

Equivalent operators : Here are some operators whose work is same.

  (a != b) is equivalent to !(a == b)
  (a > b) equivalent to (b < a)
  (a <= b) equivalent to !(b < a)  

Time Complexity : The time complexity of the above operation is O(n) where n is the size of the array.

Below is the code to illustrate the working of relational operators on array

Program 1: Relational Operator Comparison

// array comparisons using relational operators
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // declaration of array
    array<int, 5> a = { 1, 2, 3, 4, 5 };
    array<int, 5> b = { 1, 2, 3, 4, 5 };
    array<int, 5> c = { 5, 4, 3, 2, 1 };

    if (a >= b) {
        cout << "a is greater than equal to b\n";
    }
    else {
        cout << "a is neither greater than nor equal to b\n";
    }

    if (b < c) {
        cout << "b is less than c\n";
    }
    else {
        cout << "b is not lesser than c\n";
    }
    if (a >= c) {
        cout << "a is greater than equal to c\n";
    }
    else {
        cout << "a is neither greater than nor equal to c\n";
    }

    return 0;
}

Output :

a is greater than equal to b
b is less than c
a is neither greater than nor equal to c

Program 2: Relational Operator Equality

// CPP program to check for array qualities.
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // declaration of array
    array<char, 5> a = { 'a', 'b', 'c', 'd', 'e' };
    array<char, 5> b = { 'e', 'd', 'c', 'b', 'a' };
    array<char, 5> c = { 'a', 'b', 'c', 'd', 'e' };

    if (a == b) {
        cout << "a is  equal to b\n";
    }
    else {
        cout << "a is not equal to b\n";
    }

    if (b != c) {
        cout << "b is not equal to c\n";
    }
    else {
        cout << "b is equal to c\n";
    }
    if (a == c) {
        cout << "a is equal to c\n";
    }
    else {
        cout << "a is not equal to c\n";
    }

    return 0;
}

Output :

a is not equal to b
b is not equal to c
a is equal to c