Can you come up with a slick solution?

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3.40/5 (5 votes)

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As I was attending a developer conference last week, I saw a solution to a pretty usual problem. The example was given by Venkat Subramaniam, and I really liked his way about things.
So I challenge you guys to come up with a solution to the following problem:

Your boss has a range of numbers [1..9], and want you to find all the even numbers. You are about to go for the day, so you do it simple:

C#

static void Main()
{
    var intCollection = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

    // Finding even numbers
    Console.Write("Even numbers:");
    foreach (var i in intCollection)
        if (i % 2 == 0)
            Console.Write(" " + i);
    Console.WriteLine("");
}

Just as you are about to go out for some beers, your boss comes to you again and says he wants the odd numbers as well. So you do some refactoring, and some copy and pasting as well.

C#

static void Main()
{
    var intCollection = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

    FindEvenNumbers(intCollection);
    FindOddNumbers(intCollection);
}

private static void FindEvenNumbers(List<int> intCollection)
{
    Console.Write("Even numbers:");
    foreach (var i in intCollection)
        if (i % 2 == 0)
            Console.Write(" " + i);
    Console.WriteLine("");
}
private static void FindOddNumbers(List<int> intCollection)
{
    Console.Write("Odd numbers:");
    foreach (var i in intCollection)
        if (i % 2 != 0)
            Console.Write(" " + i);
    Console.WriteLine("");
}

You put on your coat and head for the door when your boss asks you for all numbers over 6. You are thinking about your mates starting to drink beer, and start questioning your self if all your education is worth another copy and paste. So what do you do to stop repeating your self? GL HF ;) Solutions will be voted for, and mr. Subramaniam's solution will also be posted if no one match it.

Posted 11-Jun-12 9:11am

Amund Gjersøe

Updated 11-Jun-12 9:17am

v2

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3 solutions

Solution 3

hi,
One solution is to create a simple sequential workflow which will have your main logic, rehost the workflow designer in a windows/WPF application and let your boss to change the condition of the workflow whenever he wants. It will work, but it is a little bit complex to implement.

Cheers

Posted 11-Jun-12 9:38am

Reza Ahmadi

Updated 11-Jun-12 9:39am

v3

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Tim Corey · Accepted Answer · 2012-06-11T09:32:00

You could do a simple Func<> statement like so:

C#

public static void TestArray(List<int> numbers, Func<int, bool> check)
{
    foreach (int i in numbers)
    {
        if (IsAMatch(i,check))
        {
            Console.Write(" " + i);
        }
    }
    Console.WriteLine();
}

public static bool IsAMatch(int valueToCheck, Func<int, bool> check) 
{
    return check(valueToCheck);
}

Then you could call it like so:

XML

var intCollection = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
TestArray(intCollection, x => x % 2 == 0);
TestArray(intCollection, x => x % 2 != 0);
TestArray(intCollection, x => x {gt} 6);

* Having issues with the greater than in the last statement

Amund Gjersøe · Accepted Answer · 2012-06-11T11:16:00

Original solution:

C#

static void Main()
{
    var intCollection = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

    // Finding numbers
    FindNumbers(intCollection, "Even numbers:", i => i % 2 == 0);
    FindNumbers(intCollection, "Odd numbers:", i => i % 2 != 0);
    FindNumbers(intCollection, "Numbers above 6:", i => i > 6);
            
}

       
private static void FindNumbers(List<int> intCollection, string text, Func<int,> block)
{
    Console.Write(text);
    foreach (var i in intCollection)
        if (block(i))
            Console.Write(" " + i);
    Console.WriteLine("");
}

Prints:

Even numbers: 2 4 6 8
Odd numbers: 1 3 5 7 9
Numbers above 6: 7 8 9

Good night :)

Can you come up with a slick solution?

3 solutions

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