[Posting] applying a hash table (hashtable) in C)

1. Brief description of the hash table (hashtable)

In. in the. NET Framework, hashtable is system. A container provided by the collections namespace is used to process and present key-value pairs similar to key/value. The key is usually used for quick search, and the key is case sensitive; value is used to store the value corresponding to the key. In hashtable, key/value pairs are of the object type, so hashtable can support any type of key/value pairs.

Ii. Simple operations on Hash Tables

Add a key/value pair in the hash table: hashtableobject. Add (Key, value );
Remove a 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 ConsoleProgramAll 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 the key-Value Pair
Console. writeline (De. Value); // de. Key corresponds to the key/value Key-Value Pair Value
}

4. Sort hash tables

The definition of sorting hash tables here is to re-arrange the keys in key/value pairs according to certain rules, but in fact this definition cannot be implemented, because we cannot re-arrange keys directly 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)
{
Console. Write (skey + ":");
Console. writeline (HT [skey]); // output after sorting
}

1. Brief description of the hash table (hashtable)

In. in the. NET Framework, hashtable is system. A container provided by the collections namespace is used to process and present key-value pairs similar to key/value. The key is usually used for quick search, and the key is case sensitive; value is used to store the value corresponding to the key. In hashtable, key/value pairs are of the object type, so hashtable can support any type of key/value pairs.

Ii. Simple operations on Hash Tables

Add a key/value pair in the hash table: hashtableobject. Add (Key, value );
Remove a 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 contains all the preceding operations:
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 ");