Improving queue code

Author: aubertc

source/code/projects/CQueue/CQueue/CQueue.cs

@@ -5,6 +5,7 @@ class CQueue<T>
   private int front,
     end,
     size;
+
   private T[] mArray;
 
   public CQueue(int capacity = 10)
@@ -31,11 +32,11 @@ public bool IsFull()
     return size == mArray.Length;
   }
 
-  public void Enqueue(T newItem)
+  public void Enqueue(T dataP)
   {
     if (!IsFull())
     {
-      mArray[end] = newItem;
+      mArray[end] = dataP;
       Increment(ref end);
       size++;
     }
@@ -53,8 +54,8 @@ public T Dequeue()
 
   public void Resize()
   {
-    throw new Exception(
-      "Queue Resize is not implemented - you could implement it"
+    throw new NotImplementedException(
+      "Queue Resize is not implemented."
     );
   }
 
@@ -70,6 +71,9 @@ private void Increment(ref int value)
     {
       value = 0;
     }
+    // This if statement could be replaced
+    // with
+    // value %= mArray.Length;
   }
 
   public int Capacity
@@ -82,6 +86,7 @@ public override string ToString()
     string returned = "";
     returned +=
       $"Front : {front}, end : {end}, size : {size}, capacity: {Capacity}\n";
+    // Note how the for is constructed:
     for (int i = front; i < size + front; i++)
     {
       returned += mArray[i % mArray.Length] + ":";

source/lectures/data/queue.md

@@ -78,4 +78,29 @@ Our implementation can recover the capacity of the queue by using:
 ```
 capacity = mArray.Length - size;
 ```
-.
+
+However, trying to recover the size from the `front` and `end` values is not possible.
+One could try, using
+
+```
+public int CSize
+{
+    get
+    {
+        int csize = 0;
+        if (front < end) { csize = end - front; }
+        else if (front == end) { csize = mArray.Length; }
+        else
+        {
+            csize = mArray.Length - front + end;
+        }
+        if (csize != size)
+        {
+            throw new NotImplementedException("CSize is not correctly implemented!");
+        }
+        return csize;
+    }
+}
+```
+
+but the exception would be thrown: can you figure out in which case(s) the "computed size" would be incorrect?