This article will show you , how could we use Predicate , Anonymous method and Lambdas with LINQ to find out all odd numbers from a range of number.

If we have a range of number from 1 to 20 and we want to find odd among them using LINQ .

We have three options for that

1. Calling a Predicate
2. Anonymous Method
3. Lambda

So here we can see that we need to pass a predicate to evaluate the condition.

Calling a Predicate

Function we will pass as predicate is as below

staticvoid Main(string[] args)
{
    var result = from r in
                 Enumerable.Range(1, 20).Where(GetOdd)
                 select r;
    foreach (var r in result)
    Console.WriteLine(r);
    Console.ReadKey(true);
}

We will pass this function as predicate to find odd numbers from the range of numbers.

var result = from r in
             Enumerable.Range(1, 20).Where(GetOdd)
             select r;

Program.cs

using System;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Text;

namespace ConsoleApplication25
{
    classProgram
    {
        staticvoid Main(string[] args)
        {
            var result = from r in
                         Enumerable.Range(1, 20).Where(GetOdd)
                         select r;
            foreach (var r in result)
            Console.WriteLine(r);
            Console.ReadKey(true);
        }
        staticboolGetOdd(int number)
        {
            if (number % 2 != 0)
                return true;
            else
                return false; 
        }
    }
}

Output

Using Anonymous Method

We can use anonymous method also

var result = from r in
Enumerable.Range(1, 20).Where(delegate(int number)
                                { 
                                    if (number % 2 != 0)
                                        return true;
                                        return false; })
                                select r;

Anonymous method is taking an input parameter and returning a Boolean value.

Program.cs

using System;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Text;

namespace ConsoleApplication25
{
    classProgram
    {
        staticvoid Main(string[] args)
        {
            var result = from r in
            Enumerable.Range(1, 20).Where(delegate(int number)
                                            { 
                                                if (number % 2 != 0)
                                                    return true;
                                                    return false; })
                                            select r;
            foreach (var r in result)
            Console.WriteLine(r);
            Console.ReadKey(true);
        }
    }
}

Output

Using Lambda

To make our query more readable in version 3.0 and onwards we can use Lambda instead of anonymous method also.

var result = from r in
                         Enumerable.Range(1, 20).Where(num =>num%2!=0)
                                                           select r;

Lambda is very simple returning true when reminder is 0.

Program.cs

using System;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Text;

namespace ConsoleApplication25
{
    classProgram
    {
        staticvoid Main(string[] args)
        {
            var result = from r in
                         Enumerable.Range(1, 20).Where(num =>num%2!=0)
                                                           select r;
            foreach (var r in result)
            Console.WriteLine(r);
            Console.ReadKey(true);
        }
    }
}

Output