CODEWITHSUNDEEP
c#arraysdata-structuresqueue
Osama Saad
Osama Saad

Reputation: 3

i'm trying to make queue class by c # the why dequeueing function doesn't work?

this is the class data members and getters and setters:

class Queue
{
    int[] data; //array
    int size; //size of array
    int counter; //checker if array is fully or impty
    int first; // first element of array
    int last; // last element of arry
}

fixed size constructor

public Queue(int size) { 
    data = new int[this.size];
    size = this.size;
    counter = 0;
    first = 0;
    last = 0;
}

default constructor

public Queue() { //default constructor
    data = new int[10];
    size = 10;
    counter = 0;
    first = 0;
    last = 0;
}

enqueing function "push"

public bool Enqueue(int num) { 
    bool result;
    if (counter<size)
    {
        data[last] = num;   
        last++;
        if(last == size)
            last = 0;
        counter++;
        return result = true
    }
    else
    {
        return result = false;
    }
    return result;
}

dequeueing function "pop"

public int Dequeueing() {
    int result=-1;
    // I know that i should make this nullable function but (-1) good at this time

    if (counter>0)
    {
        result = data[first];
        first++;
        if (first==size)
            first = 0;
        counter--;
    }
    return result;
}

on the main it is excute the enqueueing good but dequeueing its (first++)and (counter--) but it doesn't delete first input ** **why it doesn't delete (17)

static void Main(string[] args)
{
    Queue q1 = new Queue();
    q1.Enqueue(17);
    q1.Enqueue(20);
    q1.Enqueue(25);
    q1.Enqueue(15);
    q1.Enqueue(14);
    q1.Enqueue(13);
    q1.Dequeueing();        

    Console.ReadLine();
}

Upvotes: 0

Views: 61

Answers (2)

Vikhram
Vikhram

Reputation: 4394

Your expectation that once you do first++; and counter--;, the data[first] will be deleted is misplaced. Frankly, if it will somehow cause data[first] to be deleted then rest of your code will not work. What that code does is to simply Dequeue. The Queue bounds are marked using first and last, with the help of counter, so only those things need to change and no array element deletion needs to happen

Let me help you understand your code a bit. Your Queue class is what is called a Circular Queue. In such an implementation, you have the benefit that the amount of storage allocated for the Queue is "fixed" and determined on construction. This also implies that when you Enqueue there will be no extra memory requested and when you Dequeue there will be no memory released.

If you wish to somehow identify an unoccupied slot in the array, you can use special values. For example, making int?[] data, you can store var item = data[front]; data[front] = null before Dequeueing. Or, you can use a routine like GetQueueData to return all the elements in the Queue as a separate IEnumerable

public IEnumerable<int> GetQueueData() {
    for (int i = first, cnt = 0; cnt < counter; i = (i + 1) % size, ++cnt)
        yield return data[i];
}

Upvotes: 1

Justin Harvey
Justin Harvey

Reputation: 14672

The array named data will remain in the same state as when you created it as you have not done anything to make this otherwise.

Upvotes: 0

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