1. Brief description of the hash table (hashtable)
In. in net work, hashtable is system. A container provided by the collections namespace is used to process and present key-value pairs similar to key/. The key is usually used for quick search, and the key is case sensitive; store the value corresponding to the key. In hashtable, key/key-value pairs are of the object type, so hashtable can support any type of key/key-value pairs. Ii. Simple operations on Hash Tables
Add a key/key-value pair to the hash table: hashtableobject. Add (Key ,);
Remove a key/key-value pair in the hash table: hashtableobject. Remove (key );
Remove all elements from the hash table: hashtableobject. Clear ();
Determine whether the hash table contains the specified key: hashtableobject. Contains (key );
The following Console Program All of the above operations will be included:
Using system;
Using system. collections; // This namespace must be introduced when hashtable is used.
Class hashtable
{
Public static void main ()
{
Hashtable ht = new hashtable (); // create a hashtable instance
Ht. Add ("e", "E"); // Add key/value pairs
Ht. Add ("A", "");
Ht. Add ("C", "C ");
Ht. Add ("B", "B "); String S = (string) HT ["A"];
If (HT. Contains ("e") // checks whether the hash table contains a specific key. The return value is true or false.
Console. writeline ("the e key: exist ");
Ht. Remove ("C"); // remove a key/value pair
Console. writeline (HT ["A"]); // output
Ht. Clear (); // remove all elements
Console. writeline (HT ["A"]); // there will be no output here
}
} 3. traverse the hash table
Dictionaryentry object is required to traverse a hash table,CodeAs follows:
For (dictionaryentry de in HT) // HT is a hashtable instance.
{
Console. writeline (De. Key); // de. Key corresponds to key/key-Value Pair
Console. writeline (De.); // de. Key corresponds to key/key-Value Pair
} 4, sort the hash table
sort the hash table. The definition here is sort keys in key/key-value pairs in a specified rule and, but in fact, this definition cannot be implemented, because we cannot directly rearrange keys in hashtable. If hashtable needs to provide output of certain rules, we can adopt a work und:
arraylist akeys = new arraylist (HT. keys); // do not forget to import system. collections
akeys. sort (); // sort by letter
for (string skey in akeys)
{< Br _ extended = "true">
console. write (skey ":");
console. writeline (HT [skey]); // output after sorting
}< Br _ extended = "true"> |
