C＃|使用指定索引处的键和值插入OrderedDictionary

OrderedDictionary.Insert(Int32，Object，Object)方法用于将新条目插入到OrderedDictionary集合中，并在指定索引处使用指定键和值。

句法：

public void Insert (int index, object key, object value);

参数：

index : It is the zero-based index at which the element should be inserted.
key : It is the key of the entry to add.
value : It is the value of the entry to add. The value can be null.

例外情况：

• NotSupportedException：如果OrderedDictionary集合为只读。
• ArgumentOutOfRangeException：如果索引超出范围。

下面给出了一些示例，以更好地理解实现：

范例1：

// C# code to insert entry into
// OrderedDictionary with key and
// value at the specified index
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver method
    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");
  
        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " 
                                     + myDict.Count);
  
        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);
  
        // Inserting entry into OrderedDictionary
        // with key and value at the specified index
        myDict.Insert(2, "Geeks", "Noida");
  
        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " 
                                      + myDict.Count);
  
        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);
    }
}

输出：

Number of elements are : 5
key1 -- value1
key2 -- value2
key3 -- value3
key4 -- value4
key5 -- value5
Number of elements are : 6
key1 -- value1
key2 -- value2
Geeks -- Noida
key3 -- value3
key4 -- value4
key5 -- value5

范例2：

// C# code to insert entry into
// OrderedDictionary with key and
// value at the specified index
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver method
    public static void Main()
    {
  
        // Creating a orderedDictionary named myDict
        OrderedDictionary myDict = new OrderedDictionary();
  
        // Adding key and value in myDict
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");
  
        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " 
                                      + myDict.Count);
  
        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);
  
        // Inserting entry into OrderedDictionary
        // with key and value at the specified index
        // This should raise "ArgumentOutOfRangeException"
        // as index is out of range
        myDict.Insert(10, "E", "Elephant");
  
        // Displaying the number of element initially
        Console.WriteLine("Number of elements are : " 
                                      + myDict.Count);
  
        // Displaying the elements in myDict
        foreach(DictionaryEntry de in myDict)
            Console.WriteLine(de.Key + " -- " + de.Value);
    }
}

运行时错误：

Unhandled Exception:
System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: index

笔记：

• 如果index参数等于OrderedDictionary集合中的条目数，则将key和value参数附加到集合的末尾。
• 插入点之后的条目将向下移动以容纳新条目，并且所移动条目的索引也会更新。

参考：

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