C++ Queue::operator!=() Function

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The C++std::queue::operator!=() function for a queue is used to compare two queue objects for inequality. It checks if the queue differ in size or in their respective elements. If any element or the size of the queues are not same, it return true otherwise it return false. The time complexity of this function is linear i.e.O(n).

Syntax

Following is the syntax for std::queue::operator!=() function.

bool operator!= (const queue<T,Container>& q1, const queue<T,Container>& q2);

Parameters

• q1 − It indicates the first queue object.
• q2 − It indicates the second queue object.

Return value

This function returns true if both queues are not identical otherwise false.

Example

Let's look at the following example, where we are going to initialize the queues of same elements in the same order and observing the output.

#include <iostream>
#include <queue>
int main()
{
    std::queue<int> x;
    std::queue<int> y;
    x.push(11);
    x.push(2);
    y.push(11);
    y.push(2);
    if (x != y) {
        std::cout << "Queues are not equal." << std::endl;
    } else {
        std::cout << "Queues are equal." << std::endl;
    }
    return 0;
}

Output

Output of the above code is as follows −

Queues are equal.

Example

Consider the another scenario, where we are going to use the operator!=() function on the different sized queue.

#include <iostream>
#include <queue>
int main()
{
    std::queue<int> a;
    std::queue<int> b;
    a.push(11);
    b.push(11);
    b.push(2);
    if (a != b) {
        std::cout << "Queues are not equal." << std::endl;
    } else {
        std::cout << "Queues are equal." << std::endl;
    }
    return 0;
}

Output

Following is the output of the above code −

Queues are not equal.

Example

In the following example, we are going to perform the comparison on the empty queue and observing the output.

#include <iostream>
#include <queue>
int main()
{
    std::queue<int> a;
    std::queue<int> b;
    if (a != b) {
        std::cout << "Queues are not equal." << std::endl;
    } else {
        std::cout << "Queues are equal." << std::endl;
    }
    return 0;
}

Output

If we run the above code it will generate the following output −

Queues are equal.