C#常见的几种集合 ArrayList，Hashtable，List<T>，Dictionary<K,V> 遍历方法对比

ArrayList list = new ArrayList();
//for遍历
for (int i = 0; i < list.Count; i++)
{
  SE se = (SE)list[i];
  Console.WriteLine(se.Name);
}
//foreach遍历
foreach (Object obj in list)
{
  SE se = (SE)list[i];
  Console.WriteLine(se.Name);
}

Hashtable list = new Hashtable();

//Hashtable不能用索引访问，所以遍历一个Hashtable只能用foreache()方法

//遍历Key
foreach (Object obj in list.Keys)
{
  Console.WriteLine((string)obj);
}
//遍历Value
foreach (Object obj in list.Values)
{
  SE se = (SE)obj;
  Console.WriteLine(se.Name);
}
//同时遍历，DictionaryEntry一个结构
foreach (DictionaryEntry en in list)
{
  Console.WriteLine(se.Keys);
  COnsole.WriteLine(((SE)en.Value).Name);
}

//for遍历
for (int i = 0; i < list.Count; i++)
{
  //遍历时不需要类型转换
  Console.WriteLine(list[i]);
}
//foreach遍历
foreach (SE obj in list)
{
  //遍历时不需要类型转换
  Console.WriteLine(obj);
}

//遍历Values
foreach (SE se in list.Values)
{
  //遍历时不需要类型转换
  Console.WriteLine(se);
}

//同时遍历
foreach (KeyValuePair<string, SE> en in list)
{
  Console.WriteLine(en.Key);
  Console.WriteLine(en.Value.Name);
}
//KeyValuePair<TKey,TValue>是一个泛型结构