The Hashtable class represents a collection of key-and-value pairs that are organized based on the hash code of the key. The key is used to access the items in the collection. Hashtable.Add(Object, Object) Method is used to adds an element with the specified key and value into the Hashtable.

Syntax:

public virtual void Add(object key, object value);

Parameters:

key: It is the specified key of the element to add of type System.Object.
value: It is the specified value of the element to add of type System.Object. The value can be null.

Exceptions:

ArgumentNullException : If the key is null.
ArgumentException : If an element with the same key already exists in the Hashtable.
NotSupportedException : Either Hashtable is read-only or Hashtable has a fixed size.

Below given are some examples to understand the implementation in a better way :

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FAQs

C# | Adding an element into the Hashtable - GeeksforGeeks? ›

Add(Object, Object) Method is used to adds an element with the specified key and value into the Hashtable. Syntax: public virtual void Add(object key, object value);

Read On ›

How do you insert an element in a Hashtable? ›

To insert a new item in the table, we hash the key to determine which list the item goes on, and then insert the item at the beginning of the list. For example, to insert 11, we divide 11 by 8 giving a remainder of 3. Thus, 11 goes on the list starting at HashTable[3].

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How do you access elements in a Hashtable? ›

Each element is assigned a key (converted key). By using that key you can access the element in O(1) time. Using the key, the algorithm (hash function) computes an index that suggests where an entry can be found or inserted.

How do you add items to a Hashtable? ›

And, you can add keys and values to a hashtable using the addition operator ( + ) to add a hashtable to an existing hashtable. For example, the following statement adds a Time key with a value of Now to the hashtable in the $hash variable. You can also add values that are stored in variables.

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How does a Hashtable work internally in C#? ›

A HashTable collection stores a ( Key , Value ) pair and uses the Key to hash and obtain the storage location. The Key is immutable and cannot have duplicate entries in the HashTable .

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How to add elements in a hashtable in C#? ›

The Hashtable class represents a collection of key-and-value pairs that are organized based on the hash code of the key. The key is used to access the items in the collection. Hashtable. Add(Object, Object) Method is used to adds an element with the specified key and value into the Hashtable.

Tell Me More ›

Which method is used to add the data in a hashtable? ›

util. Hashtable. put() method of Hashtable is used to insert a mapping into a table. This means we can insert a specific key and the value it is mapping to into a particular table.

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How are items found in a hash table? ›

A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored.

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What is Hashtable in C# with example? ›

A Hashtable is a collection of key/value pairs that are arranged based on the hash code of the key. In other words, a Hashtable is used to create a collection that uses a hash table for storage.

Which is faster, Dictionary or Hashtable? ›

A Dictionary<TKey,TValue> of a specific type (other than Object) provides better performance than a Hashtable for value types. This is because the elements of Hashtable are of type Object; therefore, boxing and unboxing typically occur when you store or retrieve a value type.

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Can a Hashtable have duplicate keys? ›

No , Hashtable do not accept duplicate keys. It stores key-value pairs in hash table data structure which internally maintains an array of list.

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How do you insert an element in a HashMap? ›

put() method of HashMap is used to insert a mapping into a map. This means we can insert a specific key and the value it is mapping to into a particular map. If an existing key is passed then the previous value gets replaced by the new value. If a new pair is passed, then the pair gets inserted as a whole.

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What is the insertion order of a hashtable? ›

Hashtable does not maintains insertion order in java. LinkedHashMap maintains insertion order in java. TreeMap is sorted by natural order of keys in java. HashMap is not synchronized, hence its operations are faster as compared to Hashtable.

Get More Info Here ›