Predicate delegate type in C Sharp (C#) - Mini Project: Build & Apply

Using Predicate Delegate Type in C#

📖 Scenario: You are working on a simple program to filter a list of numbers. You want to find which numbers are even using a special kind of function called a Predicate. This helps you check each number and decide if it meets your rule.

🎯 Goal: Build a C# program that uses a Predicate<int> delegate to find all even numbers from a list of integers.

📋 What You'll Learn

Create a list of integers with exact values: 1, 2, 3, 4, 5, 6

Create a Predicate<int> delegate called isEven that checks if a number is even

Use the FindAll method with the isEven predicate to get all even numbers

Print the resulting list of even numbers separated by spaces

💡 Why This Matters

🌍 Real World

Filtering lists based on conditions is common in apps like shopping filters, contact lists, or game scores.

💼 Career

Understanding Predicate delegates helps you write clean, reusable code for filtering data in C# applications.

1

Create the list of numbers

Create a List<int> called numbers with these exact values: 1, 2, 3, 4, 5, 6.

C Sharp (C#)

using System.Collections.Generic;

// Create the list of numbers
// Your code here

Need a hint?

Use new List<int> { 1, 2, 3, 4, 5, 6 } to create the list.

2

Create the Predicate delegate

Create a Predicate<int> delegate called isEven that returns true if a number is even (divisible by 2), otherwise false.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List numbers = new List { 1, 2, 3, 4, 5, 6 };

        // Create the Predicate delegate called isEven
        // Your code here
    }
}

Need a hint?

Use a lambda expression like n => n % 2 == 0 to define the predicate.

3

Use FindAll with the Predicate

Use the FindAll method on numbers with the isEven predicate to create a new list called evenNumbers containing only even numbers.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List numbers = new List { 1, 2, 3, 4, 5, 6 };

        Predicate isEven = n => n % 2 == 0;

        // Use FindAll with isEven to get evenNumbers
        // Your code here
    }
}

Need a hint?

Call numbers.FindAll(isEven) to get the filtered list.

4

Print the even numbers

Print the numbers in evenNumbers separated by spaces using Console.WriteLine and string.Join.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List numbers = new List { 1, 2, 3, 4, 5, 6 };

        Predicate isEven = n => n % 2 == 0;

        List evenNumbers = numbers.FindAll(isEven);

        // Print the evenNumbers separated by spaces
        // Your code here
    }
}

Need a hint?

Use Console.WriteLine(string.Join(" ", evenNumbers)) to print the list.