Open In App

C# | Add key and value into StringDictionary

Improve
Improve
Like Article
Like
Save
Share
Report

StringDictionary.Add(String, String) method is used to add an entry with the specified key and value into the StringDictionary.

Syntax:

public virtual void Add (string key, string value);

Parameters:

  • key: It is the key of the entry which is to be added.
  • value: It is the value of the entry which is to be added. The value can be null.

Exceptions:

  • ArgumentNullException : If the key is null.
  • ArgumentException : It is an entry with the same key already exists in the StringDictionary.
  • NotSupportedException : If the StringDictionary is read-only.

Below programs illustrate the use of StringDictionary.Add(String, String) method:

Example 1:




// C# code to add key and value
// into the StringDictionary
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a StringDictionary named myDict
        StringDictionary myDict = new StringDictionary();
  
        // Adding key and value into the StringDictionary
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");
        myDict.Add("E", "Elephant");
  
        // Displaying the keys and values in StringDictionary
        foreach(DictionaryEntry dic in myDict)
        {
            Console.WriteLine(dic.Key + "  " + dic.Value);
        }
    }
}


Output:

d  Dog
b  Banana
c  Cat
e  Elephant
a  Apple

Example 2:




// C# code to add key and value
// into the StringDictionary
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a StringDictionary named myDict
        StringDictionary myDict = new StringDictionary();
  
        // Adding key and value into the StringDictionary
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");
  
        // It should raise "ArgumentException"
        // as an entry with the same key
        // already exists in the StringDictionary.
        myDict.Add("C", "Code");
  
        // Displaying the keys and values in StringDictionary
        foreach(DictionaryEntry dic in myDict)
        {
            Console.WriteLine(dic.Key + "  " + dic.Value);
        }
    }
}


Runtime Error:

Unhandled Exception:
System.ArgumentException: Item has already been added. Key in dictionary: ‘c’ Key being added: ‘c’

Note:

  • The key is handled in a case-insensitive manner i.e, it is translated to lowercase before it is added to the string dictionary.
  • This method is an O(1) operation.

Reference:



Last Updated : 01 Feb, 2019
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads