How to find a key in a Dictionary with C#

Find a Key

The ContainsKey method checks if a key already exists in the dictionary. The following code snippet checks if a key already exits and if not, adds it. 

if (!AuthorList.ContainsKey("Mahesh Chand"))
{
    AuthorList["Mahesh Chand"] = 20;
} 

Find a Value 

The ContainsValue method checks if a value already exists in the dictionary. The following code snippet checks if a value already exits. 

if (!AuthorList.ContainsValue(9))
{
    Console.WriteLine("Item found");
} 

Sample 

Here is the complete sample code showing how to use these methods.

// Create a dictionary with string key and Int16 value pair

Dictionary<string, Int16> AuthorList = new Dictionary<string, Int16>();

AuthorList.Add("Mahesh Chand", 35);

AuthorList.Add("Mike Gold", 25);

AuthorList.Add("Praveen Kumar", 29);

AuthorList.Add("Raj Beniwal", 21);

AuthorList.Add("Dinesh Beniwal", 84); 

// Count

Console.WriteLine("Count: {0}", AuthorList.Count); 

// Set Item value

AuthorList["Neel Beniwal"] = 9;

if (!AuthorList.ContainsKey("Mahesh Chand"))
{
    AuthorList["Mahesh Chand"] = 20;
}

if (!AuthorList.ContainsValue(9))
{
    Console.WriteLine("Item found");
}                    

// Read all items

Console.WriteLine("Authors all items:"); 

foreach (KeyValuePair<string, Int16> author in AuthorList)
{

    Console.WriteLine("Key: {0}, Value: {1}",
        author.Key, author.Value);
}