Created
April 22, 2014 18:57
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using System; | |
using System.Collections; | |
class Example | |
{ | |
public static void Main() | |
{ | |
// Create a new hash table. | |
// | |
Hashtable openWith = new Hashtable(); | |
// Add some elements to the hash table. There are no | |
// duplicate keys, but some of the values are duplicates. | |
openWith.Add("txt", "notepad.exe"); | |
openWith.Add("bmp", "paint.exe"); | |
openWith.Add("dib", "paint.exe"); | |
openWith.Add("rtf", "wordpad.exe"); | |
// The Add method throws an exception if the new key is | |
// already in the hash table. | |
try | |
{ | |
openWith.Add("txt", "winword.exe"); | |
} | |
catch | |
{ | |
Console.WriteLine("An element with Key = \"txt\" already exists."); | |
} | |
// The Item property is the default property, so you | |
// can omit its name when accessing elements. | |
Console.WriteLine("For key = \"rtf\", value = {0}.", openWith["rtf"]); | |
// The default Item property can be used to change the value | |
// associated with a key. | |
openWith["rtf"] = "winword.exe"; | |
Console.WriteLine("For key = \"rtf\", value = {0}.", openWith["rtf"]); | |
// If a key does not exist, setting the default Item property | |
// for that key adds a new key/value pair. | |
openWith["doc"] = "winword.exe"; | |
// ContainsKey can be used to test keys before inserting | |
// them. | |
if (!openWith.ContainsKey("ht")) | |
{ | |
openWith.Add("ht", "hypertrm.exe"); | |
Console.WriteLine("Value added for key = \"ht\": {0}", openWith["ht"]); | |
} | |
// When you use foreach to enumerate hash table elements, | |
// the elements are retrieved as KeyValuePair objects. | |
Console.WriteLine(); | |
foreach (DictionaryEntry de in openWith) | |
{ | |
Console.WriteLine("Key = {0}, Value = {1}", de.Key, de.Value); | |
} | |
// To get the values alone, use the Values property. | |
ICollection valueColl = openWith.Values; | |
// The elements of the ValueCollection are strongly typed | |
// with the type that was specified for hash table values. | |
Console.WriteLine(); | |
foreach (string s in valueColl) | |
{ | |
Console.WriteLine("Value = {0}", s); | |
} | |
// To get the keys alone, use the Keys property. | |
ICollection keyColl = openWith.Keys; | |
// The elements of the KeyCollection are strongly typed | |
// with the type that was specified for hash table keys. | |
Console.WriteLine(); | |
foreach (string s in keyColl) | |
{ | |
Console.WriteLine("Key = {0}", s); | |
} | |
// Use the Remove method to remove a key/value pair. | |
Console.WriteLine("\nRemove(\"doc\")"); | |
openWith.Remove("doc"); | |
if (!openWith.ContainsKey("doc")) | |
{ | |
Console.WriteLine("Key \"doc\" is not found."); | |
} | |
Console.ReadLine(); | |
} | |
} |
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