How to use Hashtable

Question

I think the Hashtable class is very strange. I can only put things into it but cannot get anything out of it. For example, I want to store information about persons and look up a person's information by his/her name. But all it can do is to find out whether a person's name is in the hashtable. It cannot get the information of the person, unless I check the entries one by one. Is there any way to make the Hashtable class work? Thanks a lot

Administrator · Answer

Hi, I think the below code can help u to understand more about how to use hashtable and to compare the objects which is contained in the hastable(not the key). And to directly get a object an from hashtable we can straight away say HashtableObject[Hashtablekey]; This statement will give u the object with the key what u want.No need to iterate Thanks edward prakash using System; namespace hashtab { using System; using System.Collections; class HashtableComparision : Hashtable, IComparable { public int CompareTo(object obj) { Person outerp = (Person)obj; IDictionaryEnumerator dic = this.GetEnumerator(); while(dic.MoveNext()) { Person innerp = (Person)dic.Value; if(innerp.name == outerp.name) { return 0; } } return 1; } } class test { public static void Main(String [] args) { Person john = new Person(); john.empno=100; john.name="Person15"; john.salary=4000; Person [] p = new Person().CreateInfo(); HashtableComparision htab = new HashtableComparision(); for(int i=0;i<10;i++) htab.Add(p[i].empno,p[i]); if(htab.CompareTo(john)== 0) Console.WriteLine("John Exsists in the list"); else Console.WriteLine("No Matches found"); Console.ReadLine(); } } class Person { public int empno; public string name; public double salary; public Person [] CreateInfo() { Person [] p = new Person[10]; for(int i=0;i<10;i++) { Person temp = new Person(); temp.empno = i+1; temp.name = "Person" + (i + 1); temp.salary = 3000 * i; p[i] = temp; } return p; } } }

Administrator · Answer

I use it as in the example: public Hashtable Metody=new Hashtable(); //...set... if(Metody.Contains(object_key)) Metody[object_key]=object_value; else Metody.Add(object_key,object_value); //...get... ObjectType result=(ObjectType)Metody[object_key]; It'a a smart class to save and get object by key value, not index of item.

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