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  1. #include <iostream>
  2. #include <queue> // Required for using the queue container
  3. using namespace std;
  4.  
  5. int main() {
  6.     // 1. Initialize an empty queue of integers
  7.     queue<int> q1; //
  8.  
  9.     // push(x): Adds elements to the back of the queue
  10.     q1.push(10); // 10 is the FIRST element in
  11.     q1.push(20); //
  12.     q1.push(30); // 30 is the LAST element in
  13.  
  14.     // size(): Returns the current number of elements
  15.     cout << "Queue size after PUSH: " << q1.size() << endl; // Output: 3
  16.  
  17.     // front(): Accesses the element at the front (10)
  18.     cout << "Front element: " << q1.front() << endl; // Output: 10
  19.  
  20.     // back(): Accesses the element at the back (30)
  21.     cout << "Back element: " << q1.back() << endl; // Output: 30
  22.  
  23.     // pop() removes the front element
  24.     q1.pop(); // The queue after pop: 20, 30
  25.  
  26.     // Final empty() check
  27.     cout << "Empty? " << (q1.empty() ? "Yes" : "No") << endl; // Output: No
  28.     return 0;
  29. }
Success #stdin #stdout 0s 5324KB
comments (?)
stdin
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Standard input is empty
stdout
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Queue size after PUSH: 3
Front element: 10
Back element: 30
Empty? No
https://ideone.com/ubpGxr
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

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