C＃|将OrderedDictionary元素复制到指定索引处的Array实例

OrderedDictionary.CopyTo(Array，Int32)方法用于将OrderedDictionary元素复制到指定索引处的一维Array对象。

句法：

public void CopyTo (Array array, int index);

参数：

array: It is the one-dimensional Array which is the destination of the DictionaryEntry objects copied from OrderedDictionary. The Array must have zero-based indexing.

index: it is the zero-based index in array at which copying begins.

注意： OrderedDictionary.CopyTo(Array，Int32)方法不提供任何保证来维持OrderedDictionary集合中元素的顺序。

下面的程序说明了上述方法的用法：

范例1：

// C# code to copy OrderedDictionary to
// Array instance at the specified index
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();
  
        // Adding key and value in myDict
        myDict.Add("key1", "value1");
        myDict.Add("key2", "value2");
        myDict.Add("key3", "value3");
        myDict.Add("key4", "value4");
        myDict.Add("key5", "value5");
  
        DictionaryEntry[] myArr = new DictionaryEntry[myDict.Count];
  
        // Copying OrderedDictionary to Array
        // instance at the specified index
        myDict.CopyTo(myArr, 0);
  
        // Displaying elements in myArr
        for (int i = 0; i < myArr.Length; i++) {
            Console.WriteLine(myArr[i].Key + "-->" 
                                + myArr[i].Value);
        }
    }
}

输出：

key3-->value3
key4-->value4
key5-->value5
key2-->value2
key1-->value1

范例2：

// C# code to copy OrderedDictionary to
// Array instance at the specified index
// that give ArgumentOutOfRangeException
// due to the negative index
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();
  
        // Adding key and value in myDict
        myDict.Add("C", "1");
        myDict.Add("C++", "2");
        myDict.Add("Java", "3");
        myDict.Add("C#", "4");
  
        DictionaryEntry[] myArr = new DictionaryEntry[myDict.Count];
  
        // Copying OrderedDictionary to Array
        // instance at the specified index
        // This will raise "ArgumentOutOfRangeException"
        // as index is less than 0
        myDict.CopyTo(myArr, -2);
  
        // Displaying elements in myArr
        for (int i = 0; i < myArr.Length; i++) {
            Console.WriteLine(myArr[i].Key + "-->" 
                                + myArr[i].Value);
        }
    }
}

运行时错误：

Unhandled Exception:
System.ArgumentOutOfRangeException: Non-negative number required.
Parameter name: arrayIndex

参考：

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