C# | Dictionary.ContainsKey() Method
Last Updated :
01 Feb, 2019
This method is used to check whether the Dictionary<TKey,TValue> contains the specified key or not.
Syntax:
public bool ContainsKey (TKey key);
Here, the key is the Key which is to be located in the Dictionary.
Return Value: This method will return true if the Dictionary contains an element with the specified key otherwise, it returns false.
Exception: This method will give ArgumentNullException if the key is null.
Below are the programs to illustrate the use of Dictionary<TKey,TValue>.ContainsKey() Method:
Example 1:
using System;
using System.Collections.Generic;
class GFG {
public static void Main()
{
Dictionary< string , string > myDict =
new Dictionary< string , string >();
myDict.Add( "Australia" , "Canberra" );
myDict.Add( "Belgium" , "Brussels" );
myDict.Add( "Netherlands" , "Amsterdam" );
myDict.Add( "China" , "Beijing" );
myDict.Add( "Russia" , "Moscow" );
myDict.Add( "India" , "New Delhi" );
if (myDict.ContainsKey( "India" ))
Console.WriteLine( "Key : India is present" );
else
Console.WriteLine( "Key : India is absent" );
}
}
|
Output:
Key : India is present
Example 2:
using System;
using System.Collections.Generic;
class GFG {
public static void Main()
{
Dictionary< string , string > myDict =
new Dictionary< string , string >();
myDict.Add( "Australia" , "Canberra" );
myDict.Add( "Belgium" , "Brussels" );
myDict.Add( "Netherlands" , "Amsterdam" );
myDict.Add( "China" , "Beijing" );
myDict.Add( "Russia" , "Moscow" );
myDict.Add( "India" , "New Delhi" );
if (myDict.ContainsKey( "USA" ))
Console.WriteLine( "Key : USA is present" );
else
Console.WriteLine( "Key : USA is absent" );
}
}
|
Output:
Key : USA is absent
Reference:
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