The **`queue.empty()` function** in C++ returns a `true (1)` value if the queue is empty. Otherwise, it returns `false (0)`. In short, this function is used to check if the queue is empty or not.

Figure 1 shows the visual representation of the `queue.empty()` function.

In order to use the `queue.empty()` function, we must include `queue` in the program, as shown below:

```c++
#include <queue>
```
#     
#  Syntax

```c++
queue_name.empty()
// where the queue_name is the name of the queue
```
#     
#  Parameter

This function does not require a parameter.

##   
## Return value

If the queue is empty, the `queue.empty()` function returns a `true (1)` value. Otherwise, it returns `false (0)`.

##   
## Example

#include <iostream>
//header file
#include <queue>
using namespace std;

int main() {
  //filled queue
  queue<int> queue1;
    queue1.push(1);
    queue1.push(3);
    queue1.push(5);
    queue1.push(2);
    queue1.push(0);
    //queue1 = 1->3->5->2->0
    cout<<"The queue1 is empty: \n"<<queue1.empty()<<"\n"; 

  //empty queue  
  queue<int> queue2;
    cout<<"The queue2 is empty: \n"<<queue2.empty(); 
}

#    
## Explanation
In the code above, we have two queues, `queue1` and `queue2`. In `queue1`, we push five items so that it is not empty anymore. Therefore, when we call the `empty()` function on `queue1`, the function returns `0`. However, when we call the `empty` function on `queue2`, which is empty, the function returns `1`.

What is queue.empty() in C++?

Syntax

Parameter

Return value

Example

Explanation