C# program to check if a value is in an array

Use the Array.Exists method to check if a value is in an array or not. This method returns a boolean value indicating whether the specified element exists in the array.

Syntax

Following is the syntax for Array.Exists method −

public static bool Exists<T>(T[] array, Predicate<T> match)

Parameters

• array − The one-dimensional array to search.

• match − A predicate that defines the conditions of the element to search for.

Return Value

Returns true if the array contains an element that matches the conditions defined by the specified predicate; otherwise, false.

Using Array.Exists with Lambda Expression

The most common way to use Array.Exists is with a lambda expression to define the search condition −

Example

using System;

public class Demo {
   public static void Main() {
      string[] strArray = new string[] {"keyboard", "screen", "mouse", "charger"};
      
      bool res1 = Array.Exists(strArray, ele => ele == "harddisk");
      Console.WriteLine("harddisk exists: " + res1);
      
      bool res2 = Array.Exists(strArray, ele => ele == "keyboard");
      Console.WriteLine("keyboard exists: " + res2);
   }
}

The output of the above code is −

harddisk exists: False
keyboard exists: True

Using Array.Exists with Different Data Types

Example

using System;

public class Demo {
   public static void Main() {
      int[] numbers = {10, 20, 30, 40, 50};
      
      bool hasEven = Array.Exists(numbers, n => n % 2 == 0);
      Console.WriteLine("Array contains even number: " + hasEven);
      
      bool hasGreaterThan35 = Array.Exists(numbers, n => n > 35);
      Console.WriteLine("Array contains number > 35: " + hasGreaterThan35);
      
      bool hasNegative = Array.Exists(numbers, n => n 

The output of the above code is −

Array contains even number: True
Array contains number > 35: True
Array contains negative number: False


Using Array.Exists with Custom Objects

Example

using System;

public class Person {
   public string Name { get; set; }
   public int Age { get; set; }
   
   public Person(string name, int age) {
      Name = name;
      Age = age;
   }
}

public class Demo {
   public static void Main() {
      Person[] people = {
         new Person("John", 25),
         new Person("Alice", 30),
         new Person("Bob", 22)
      };
      
      bool hasAlice = Array.Exists(people, p => p.Name == "Alice");
      Console.WriteLine("Alice exists: " + hasAlice);
      
      bool hasAdult = Array.Exists(people, p => p.Age >= 21);
      Console.WriteLine("Adult exists: " + hasAdult);
   }
}


The output of the above code is −

Alice exists: True
Adult exists: True


Conclusion

The Array.Exists method provides an efficient way to check if a value exists in an array using a predicate function. It works with any data type and allows flexible search conditions using lambda expressions, making it ideal for both simple value checks and complex object searches.