C＃|从哈希表中删除所有元素

Hashtable类表示键和值对的集合，这些键和值对是根据键的哈希码进行组织的。该键用于访问集合中的项目。 Hashtable.Clear方法用于从Hashtable中删除所有元素。

句法：

myTable.Clear()

在这里， myTable是哈希表的名称。

例外：如果Hashtable是只读的，则此方法将提供NotSupportedException。

例子：

// C# code to remove all elements
// from the Hashtable
using System;
using System.Collections;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a Hashtable
        Hashtable myTable = new Hashtable();
  
        // Adding elements in Hashtable
        myTable.Add("2", "Even & Prime");
        myTable.Add("3", "Odd & Prime");
        myTable.Add("4", "Even & non-prime");
        myTable.Add("9", "Odd & non-prime");
  
        // Print the number of entries in Hashtable
        Console.WriteLine("Total number of entries in Hashtable : " 
                                                  + myTable.Count);
  
        // To remove all elements from Hashtable
        myTable.Clear();
  
        // Print the number of entries in Hashtable
        Console.WriteLine("Total number of entries in Hashtable : " 
                                                  + myTable.Count);
  
        // Adding elements in Hashtable
        myTable.Add("g", "geeks");
        myTable.Add("c", "c++");
        myTable.Add("d", "data structures");
  
        // Print the number of entries in Hashtable
        Console.WriteLine("Total number of entries in Hashtable : " 
                                                  + myTable.Count);
  
        // To remove all elements from Hashtable
        myTable.Clear();
  
        // Print the number of entries in Hashtable
        Console.WriteLine("Total number of entries in Hashtable : " 
                                                   + myTable.Count);
    }
}

输出：

Total number of entries in Hashtable : 4
Total number of entries in Hashtable : 0
Total number of entries in Hashtable : 3
Total number of entries in Hashtable : 0

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.collections.hashtable.clear?view=netframework-4.7.2