CPP Queue test

Simple Note

Code

#include <iostream> 
#include <queue>

using namespace std;

/** Test basic operations of queue.
 *
 * From http://www.cplusplus.com/reference/queue/queue/
 *        queues are a type of container adaptor, specifically designed to operate
 *        in a FIFO context (first-in first-out), where elements are inserted into
 *        one end of the container and extracted from the other.
 *
 *        queues are implemented as containers adaptors, which are classes that use
 *        an encapsulated object of a specific container class as its underlying container,
 *        providing a specific set of member functions to access its elements. Elements are
 *        pushed into the "back" of the specific container and popped from its "front".
 *
 * Tested functions:
 * http://www.cplusplus.com/reference/queue/queue/empty/
 * empty: bool empty ( ) const;
 *        Returns whether the queue is empty: i.e. whether its size is zero.
 *
 * http://www.cplusplus.com/reference/queue/queue/size/
 * size: size_type size ( ) const;
 *        Returns the number of elements in the queue.
 *
 * http://www.cplusplus.com/reference/queue/queue/push/
 * push: void push (const value_type& val);
 *        Adds a new element at the end of the queue, after its current last element.
 *        The content of this new element is initialized to val.
 *
 * http://www.cplusplus.com/reference/queue/queue/pop/
 * pop: void pop ( );
 *        Removes the next element in the queue, effectively reducing its size by one.
 *        The element removed is the "oldest" element in the queue whose value can be
 *        retrieved by calling member queue::front.
 *
 *        NOTE: pop probably cause runtime error if queue is empty
 *
 * http://www.cplusplus.com/reference/queue/queue/front/
 * front: value_type& front(); or const value_type& front() const;
 *        Returns a reference to the next element in the queue. This is the "oldest" element in
 *        the queue and the same element that is popped out from the queue when queue::pop is called.
 *
 *        NOTE: front probably cause runtime error if queue is empty
 *
 * http://www.cplusplus.com/reference/queue/queue/back/
 * back: value_type& back(); or const value_type& back() const;
 *        Returns a reference to the last element in the queue. This is the "newest" element in
 *        the queue (i.e. the last element pushed into the queue).
 *
 *        NOTE: back probably cause runtime error if queue is empty
 *
 */

queue<int> testEmptySizePush (queue<int> intQueue);
queue<int> testFrontBack (queue<int> intQueue);
queue<int> testPop (queue<int> intQueue);

int main() {
    queue<int> intQueue;

    intQueue = testEmptySizePush (intQueue);
    intQueue = testFrontBack (intQueue);
    intQueue = testPop (intQueue);

    system("PAUSE");
    return 0;
}
queue<int> testEmptySizePush (queue<int> intQueue) {
    cout << "function testEmptySizePush" << endl;
    // test empty and size
    cout << "is intQueue empty? " << (intQueue.empty()? "true" : "false") << endl;
    cout << "size of intQueue is: " << intQueue.size() << endl;
    cout << "push 3, 5 and 7 into intQueue" << endl;
    // test push
    intQueue.push(3);
    intQueue.push(5);
    intQueue.push(7);
    // test empty and size again
    cout << "is intQueue empty? " << (intQueue.empty()? "true" : "false") << endl;
    cout << "size of intQueue is: " << intQueue.size() << endl << endl;
    return intQueue;
}
queue<int> testFrontBack (queue<int> intQueue) {
    cout << "function testFrontBack" << endl;
    if (!intQueue.empty()) {
        // test front
        cout << "current first value is: " << intQueue.front() << endl;
        cout << "add 5 to first value" << endl;
        intQueue.front() += 5;
        cout << "modified first value is: " << intQueue.front() << endl;

        // test back
        cout << "current last value is: " << intQueue.back() << endl;
        cout << "add 5 to last value" << endl;
        intQueue.back() += 5;
        cout << "modified last value is: " << intQueue.back() << endl << endl;
    }
    return intQueue;
}
queue<int> testPop (queue<int> intQueue) {
    cout << "function testPop" << endl;
    if (!intQueue.empty()) {
        // test pop
        cout << "first value before pop is: " << intQueue.front() << endl;
        cout << "last value before pop is: " << intQueue.back() << endl;
        cout << "pop first value" << endl;
        intQueue.pop();
        cout << "first value after pop is: " << intQueue.front() << endl;
        cout << "last value after pop is: " << intQueue.back() << endl << endl;
    }
    return intQueue;
}

Result

Reference

queue - C++ Reference
http://www.cplusplus.com/reference/queue/queue/

Download

queue.cpp
https://github.com/benbai123/C_Cplusplus_Practice/blob/master/CPP/CPP_Basic/CPP_Basic_Data_Structures/queue/queue/queue.cpp