Hash table

A Hashtable is a collection of key/value pairs where the keys need to be unique but the values need not be.

You can look up a value in the Hashtable using its key.

A Hashtable (or its generic equivalent Dictionary) is therefore suitable when you need keyed access to a collection. For example:

Hashtable ht = new Hashtable();

ht.Add("Akash", 1);

ht.Add("Vulpes", 2);

// get value for Akash

int value = (int)ht["Akash"]; // 1

Notice that a Hashtable stores everything internally as type System.Object. When retrieving a value, you therefore have to cast it to its actual type. This is unnecessary when using Dictionary which stores the keys and values using their actual types and doesn't require boxing/unboxing when the keys or values are value types (int, double, bool etc).

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Vulpes14y ago
Accepted answer
A Hashtable is a collection of key/value pairs where the keys need to be unique but the values need not be.

You can look up a value in the Hashtable using its key.

A Hashtable (or its generic equivalent Dictionary) is therefore suitable when you need keyed access to a collection. For example:

Hashtable ht = new Hashtable();
ht.Add("Akash", 1);
ht.Add("Vulpes", 2);

// get value for Akash

int value = (int)ht["Akash"]; // 1

Notice that a Hashtable stores everything internally as type System.Object. When retrieving a value, you therefore have to cast it to its actual type. This is unnecessary when using Dictionary which stores the keys and values using their actual types and doesn't require boxing/unboxing when the keys or values are value types (int, double, bool etc).
Akash Ahlawat14y ago
Thanks guys.
Jignesh Trivedi14y ago
hi,

A HashTable collection stores a (Key and Value) pair and uses the "Key" to hash and obtain the storage location.
The "Key" is immutable and cann't have duplicate entries in the HashTable.
it also provided a indexer.

u can learn more from
http://msdn.microsoft.com/en-us/library/7b3y50ay.aspx
hope this help,