C# | Add key and value into StringDictionary
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:
- https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.stringdictionary.add?view=netframework-4.7.2