C# | Remove entry with specified key from the StringDictionary
StringDictionary.Remove(String) method is used to remove the entry with the specified key from the string dictionary.
Syntax:
public virtual void Remove (string key);
Here, key is the key of the entry to remove.
Exceptions:
- ArgumentNullException: If the key is null.
- NotSupportedException: If the StringDictionary is read-only.
Below programs illustrate the use of StringDictionary.Remove(String) method:
Example 1:
// C# code to remove the entry // with the specified key from // 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" ); myDict.Add( "F" , "Fish" ); // Displaying the keys and values in StringDictionary Console.WriteLine( "The number of key/value pairs are : " + myDict.Count); foreach (DictionaryEntry dic in myDict) { Console.WriteLine(dic.Key + " " + dic.Value); } // Removing the entry with the specified // key from the StringDictionary myDict.Remove( "D" ); // Displaying the keys and values in StringDictionary Console.WriteLine( "The number of key/value pairs are : " + myDict.Count); foreach (DictionaryEntry dic in myDict) { Console.WriteLine(dic.Key + " " + dic.Value); } } } |
Output:
The number of key/value pairs are : 6 b Banana c Cat a Apple f Fish d Dog e Elephant The number of key/value pairs are : 5 b Banana c Cat a Apple f Fish e Elephant
Example 2:
// C# code to remove the entry // with the specified key from // 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" ); myDict.Add( "F" , "Fish" ); // Displaying the keys and values in StringDictionary Console.WriteLine( "The number of key/value pairs are : " + myDict.Count); foreach (DictionaryEntry dic in myDict) { Console.WriteLine(dic.Key + " " + dic.Value); } // Removing the entry with the specified // key from the StringDictionary // This should raise "ArgumentNullException" // as the key is null myDict.Remove( null ); // Displaying the keys and values in StringDictionary Console.WriteLine( "The number of key/value pairs are : " + myDict.Count); foreach (DictionaryEntry dic in myDict) { Console.WriteLine(dic.Key + " " + dic.Value); } } } |
Runtime Error:
Unhandled Exception:
System.ArgumentNullException: Value cannot be null.
Parameter name: key
Note:
- If the StringDictionary does not contain an element with the specified key, the StringDictionary remains unchanged. No exception is thrown.
- The key is handled in a case-insensitive manner, i.e, it is translated to lowercase before it is used to find the entry to remove from the StringDictionary.
- This method is an O(1) operation.
Reference:
- https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.stringdictionary.remove?view=netframework-4.7.2
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