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Stack.cs
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91 lines (77 loc) · 2.06 KB
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using System;
using System.Collections;
using System.Collections.Generic;
namespace StackUsingArray
{
public class Stack<T> : IEnumerable<T>
{
T[] _items = new T[0];
int _size;
public void Push(T item)
{
if(_size == _items.Length)
{
int _newSize = _size == 0 ? 4 : _size * 2;
T[] newArray = new T[_newSize];
_items.CopyTo(newArray, 0);
_items = newArray;
}
_items[_size++] = item;
}
public T Pop()
{
if(_size == 0)
{
throw new InvalidOperationException("Stack is empty");
}
T item = _items[--_size];
//This is minor improvement in this process from author's implementation
if (_size > 0 && _items.Length <= _size/4)
{
int _newSize = _size / 2;
T[] newArray = new T[_newSize];
_items.CopyTo(newArray, 0);
_items = newArray;
}
return item;
}
public T Peek()
{
if (_size == 0)
{
throw new InvalidOperationException("Stack is empty");
}
return _items[_size-1];
}
public int Count
{
get
{
return _size;
}
}
public void Clear()
{
/*if (!typeof(T).IsValueType)
{
for (int i = 0; i < _size; i++)
{
_items[i] = default(T);
}
}*/
_size = 0;
_items = new T[_size];
}
public IEnumerator<T> GetEnumerator()
{
for(int i=_size-1;i >= 0; --i)
{
yield return _items[i];
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}
}