Hashtable in C# represents a collection of key/value pairs which maps keys to value.

Any non-null object can be used as a key but a value can. We can retrieve items

from hashTable to provide the key. Both keys and values are Objects.

The commonly used functions in Hashtable are:

  •    Add                     : To add a pair of value in HashTable
  •    ContainsKey       : Check if a specified key exist or not
  •    ContainsValue    : Check the specified Value exist in HashTable
  •    Remove              : Remove the specified Key and corresponding Value
Add : To add a pair of value in HashTable

  Syntax    : HashTable.Add(Key,Value)

  Key          : The Key value

  Value      : The value of corresponding key

  Hashtable ht;

  ht.Add("1", "Sunday");

ContainsKey : Check if a specified key exist or not

  Synatx     : bool HashTable.ContainsKey(key)

  Key           : The Key value for search in HahTable

  Returns    : return true if item exist else false

  ht.Contains("1");

ContainsValue : Check the specified Value exist in HashTable

  Synatx       : bool HashTable.ContainsValue(Value)

  Value         : Search the specified Value in HashTable

  Returns     : return true if item exist else false

  ht.ContainsValue("Sunday")

Remove : Remove the specified Key and corresponding Value

  Syntax     : HashTable.Remove(Key)

  Key          : The key of the element to remove

  ht.Remove("1");

Code
  Hashtable ht = new Hashtable();
//creating hashtable
        int c = 0; //for key
        public frmHashTable()
        {
            InitializeComponent();
        }
 
        private void btnAdd_Click(object sender, EventArgs e)
        {
            if (txtDisplay.Text != "")
            {
                c++;
                ht.Add(c,txtDisplay.Text);
//adding value to hashtable.
            }
            txtDisplay.Text = "";
        }
 
        private void btnDisplay_Click(object sender, EventArgs e)
        {
            int x;
            x= Convert.ToInt32(txtDisplay.Text);
//converting text box text to integer
            if (ht.ContainsKey(x))
//checking whether hastable contains particular key or not.
                MessageBox.Show(ht[x].ToString());
            txtDisplay.Text= "";
        }
 
        private void btnsearch_Click(object sender, EventArgs e)
        {
            if (ht.ContainsKey(Convert.ToInt32(txtDisplay.Text)))
                MessageBox.Show("Find");
            else
                MessageBox.Show("Key not found");
            txtDisplay.Text= "";
        }
 
        private void btnRemove_Click(object sender, EventArgs e)
        {
            int x;
            x= Convert.ToInt32(txtDisplay.Text);
            if (ht.ContainsKey(x))
            {
                ht.Remove(x); //removing value from hashtable.
                MessageBox.Show("Deleted");
            }
            else
                MessageBox.Show("Key not found");
            txtDisplay.Text= "";
        }

 

Screen Shot

 

 

  Modified On Nov-30-2017 12:33:15 AM

Leave Comment