C# Discussion Boards - CodeProject

Eddy Vluggen1-Oct-13 0:31

Eddy Vluggen

1-Oct-13 0:31

OOPS and design patterns are different concepts. What's to discuss, outside of the definition the Wiki gives and the well-known patterns?

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

Keith Barrow1-Oct-13 1:01

Keith Barrow

1-Oct-13 1:01

You are going to be better off either using the search built into code project than asking here.

Ass Eddie says, OOP and design patterns are different concepts. You get design patterns for non-OO languages, though good OO-based design patterns help you adhere to OOP.
You might want to search for the "Four Pillars of OO", there is a lot of stuff out there about this. You should learn, and more importantly understand, what they are, what they mean and how this expresses itself in your chosen language. You'll save yourself a world of pain and spaghetti code in the future if/when you manage this.

Design Patterns generically are well-know (and defined) solutions to common problems. Really the pattern is a name given to such a thing,so we can discuss this as shorthand. The chances are you've actually used or implemented a pattern without knowing it. For example,c# events are an implementation of the observer pattern, so if you used an event you've unwittingly used an observer patter, There are lots of these patterns (and pseudo-patterns and anti-patterns) on the net - find out which the common ones are, and implement them.

PB 369,783 wrote:
I just find him very unlikeable, and I think the way he looks like a prettier version of his Mum is very disturbing.[^]

Abhinav S1-Oct-13 1:17

Abhinav S

1-Oct-13 1:17

If you are looking for articles on OOPS just do a search here[^]. It should give you tons of information to sift through.

Apps - Color Analyzer | Arctic | XKCD | Sound Meter | Speed Dial

Govindaraj Rangaraj1-Oct-13 4:14

Govindaraj Rangaraj

1-Oct-13 4:14

Am sorry for not being clear, I meant to say OOPS, Design principles and pattern. My intention was not to link OOPS with design patterns though. Anyways thanks to Abhinav S for sharing the link to search page.

The intention of this question is to find any forum topic to go through some real-world issues faced on these concepts (wrong usage I mean) and the discussion about how to solve those, rather than going through the tutorials on Dog, cat, apple, mango, etc.

Re: OOPS, deisgn patterns and principles

Eddy Vluggen1-Oct-13 5:00

Eddy Vluggen

1-Oct-13 5:00

justgovi wrote:
to go through some real-world issues faced

There is no list of specific problems that get solved using OOPS/design patterns. You're looking at dishes where you can use a fork, while you should study the fork - that way you'll be able to explain why soup won't work, even without having a pointer to a previous real life pain.

..and we do have articles on various patterns that use "real world" examples. Yet, that's what they are; examples. An example of a for-loop does not show where a for-loop would be beneficial (compared to a while loop), it doesn't convey the abstract idea.

As for the OO-principles, they're general guidelines. Each of those guidelines comes with a reasoning.

justgovi wrote:
wrong usage I mean

Google for the anti-patterns and you'll find them; God objects, ravioli-code and much more.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

GuyThiebaut1-Oct-13 21:47

GuyThiebaut

1-Oct-13 21:47

For design patterns grab yourself a copy of the Head First Design Patterns book - it's a decent introduction as it uses examples. The book does use Java as the language to illustrate the patterns however if you are familiar with C# this should be no problem.

“That which can be asserted without evidence, can be dismissed without evidence.”

― Christopher Hitchens

Re: OOPS, deisgn patterns and principles

Keith Barrow2-Oct-13 0:32

Keith Barrow

2-Oct-13 0:32

Seconded. This is a really good introduction to design patterns.

PB 369,783 wrote:
I just find him very unlikeable, and I think the way he looks like a prettier version of his Mum is very disturbing.[^]

Arrays

Sta_Horse30-Sep-13 23:35

Sta_Horse

30-Sep-13 23:35

Hi
I am learning programing, C# and I am on Arrays part. So I have this code and I don't understand.

static void Main(string[] args)
        {
            int[] n = new int[10];
            int i, j;

            //initialize elements of array n
            for (i = 0; i < 10; i++)
            {
                n[i] = i + 100;
            }

            /* output each array element's value */
            for (j = 0; j < 10; j++)
            {
                Console.WriteLine("Element [{0}] = {1}", j, n[j]);
            }
            Console.ReadKey();
        }

Firstly I would like to know, how can I return values of i for loop, without using j for loop.. and why j for loop was used to display output.

Garth J Lancaster30-Sep-13 23:50

Garth J Lancaster

30-Sep-13 23:50

What you need to understand is more fundamental than that

i & j are arbitrary - you can have anything as long as it is an integer - furthermore, you can re-use the same integer where both i and j are used in your diagram

so

int myArrayCounter;

is also valid and will do (and likely better than 'i' or 'j').

What's really important, is that you realise

a) you have an array of 10 integers 'n'

b) the counter required to access the elements of the array could have any of these values 0,1,2,3,4,5,6,7,8,9

you really need to read your textbook/talk with your teacher/tutor

you can start by drawing the loop on paper

Sta_Horse wrote:
int[] n = new int[10];

means

n[0] = undefined
..
n[9] = undefined

(because the array hasnt had its values set to zero)

Sta_Horse wrote:
//initialize elements of array n
for (i = 0; i < 10; i++)
{
n[i] = i + 100;
}

So, on the first loop, i = 0, yes ? so replacing i with '0', gives n[0] = 0+100 = 100
on the second loop, i = 1 - so n[1] = 1+100 = 101
..
on the last loop, i=9, so n[9] = 9+100 = 109

n[0] = 100
n[1] = 101
... you get the picture
[n9] = 109

'g'

harold aptroot1-Oct-13 1:47

harold aptroot

1-Oct-13 1:47

In C#, just like in Java, arrays are in fact initialized to zero/null (the CLR allows value types to have a parameterless constructor and will invoke it for every element in a new array and you could make an array filled with non-zero that way - but you can't create such a type in C#).

Garth J Lancaster1-Oct-13 2:10

Garth J Lancaster

1-Oct-13 2:10

oh - ok, ta for that

Pete O'Hanlon30-Sep-13 23:52

Pete O'Hanlon

30-Sep-13 23:52

Okay, what's happening here is that you're using two loops to reference the same array elements. Now, I'm not sure what you mean by returning the value here, because the Main method is void, so it doesn't return anything. If, you're talking about how you return an array from a method, you would declare the method with the array type as the method type, e.g. public int[] GetValues(). If you wanted to compress your loops into one loop, you would move the Console.WriteLine immediately after the line n[i] = ....

Chill _Maxxx_

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

OriginalGriff30-Sep-13 23:52

OriginalGriff

30-Sep-13 23:52

You presumably know how a for loop works - but I'll recap just in case:

for (init; test; alter)

Where:
init sets up the initial conditions - in your case, it sets i or j to zero.
test checks to see if the loop should continue - if test is true, it will.
alter allows you to modify the conditions so the the test will eventually become false.

So in your first loop, the value of i changes by one each time (in the second loop, the same thing happens to j) so each time the loop executes, it accesses a different element of teh array, and sets it to a different value.

For the second loop, it outputs each element in sequence.
There is no particular reason why the person who wrote that used separate variables i and j for the two loops - probably just for clarity - they could be the same variable without affecting the rest of the code.

Personally, I would change it slightly and declare the loop guard variable inside the loop:

static void Main(string[] args)
    {
    int[] n = new int[10];
    //initialize elements of array n
    for (int i = 0; i < 10; i++)
        {
        n[i] = i + 100;
        }

    // output each array element's value
    for (int j = 0; j < 10; j++)
        {
        Console.WriteLine("Element [{0}] = {1}", j, n[j]);
        }
    Console.ReadKey();
    }

As this makes it clearer that i and j are only relevant (or indeed available) inside the loop. Again, the name i could be used for both loops:

static void Main(string[] args)
    {
    int[] n = new int[10];
    //initialize elements of array n
    for (int i = 0; i < 10; i++)
        {
        n[i] = i + 100;
        }

    // output each array element's value
    for (int i = 0; i < 10; i++)
        {
        Console.WriteLine("Element [{0}] = {1}", i, n[i]);
        }
    Console.ReadKey();
    }

The only instant messaging I do involves my middle finger.

How can i do a calculation in datagridview

V.1-Oct-13 2:22

1-Oct-13 2:22

It's an "example".

the first loop defines each element in the array, the second loop runs through it to show in output that you have an array with filled values.

Normally you fill your array in one class and use the values somewhere else (in another class, method, ... eg) not immediately after initialization.

in short, the example just shows -> in -> out.

V.

(MQOTD Rules and previous Solutions )

ganesh89_babu30-Sep-13 20:40

ganesh89_babu

30-Sep-13 20:40

<pre lang="c#">

Re: How can i do a calculation in datagridview

Abhinav S30-Sep-13 22:35

Abhinav S

30-Sep-13 22:35

Here[^] is a video on this topic.

Apps - Color Analyzer | Arctic | XKCD | Sound Meter | Speed Dial

How to extract links from a div

faiza.butt8930-Sep-13 14:53

faiza.butt89

30-Sep-13 14:53

Hello everyone,

I am working on a project and need your help. I have a div having the search results in the form of links or URLs . Now I want to save them in a file. Can anyone guide me that how can I extract and save those links from div to variables or any simple data structures like array or arraylist.
Waiting for quick response!

Thanks in advance.

PIEBALDconsult30-Sep-13 15:02

PIEBALDconsult

30-Sep-13 15:02

Xpath?

Abhinav S30-Sep-13 17:15

Abhinav S

30-Sep-13 17:15

Parse the div content and look for the a or href tags within that text.

Apps - Color Analyzer | Arctic | XKCD | Sound Meter | Speed Dial

faiza.butt891-Oct-13 4:16

faiza.butt89

1-Oct-13 4:16

Thank you for reply. Actually now I am trying t parse div but y code is not working. Here it is :

HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
doc.Load(this.Page.MapPath("~/Default2.aspx"));
HtmlNodeCollection bodyNodes = doc.DocumentNode.SelectNodes("//div[@id='wrapper']/a[@href]");
foreach (var node in bodyNodes)
{
    string href = node.Attributes["href"].Value;
}

But the selected nodes are empty. May be because it only has content on runtine otherwise its empty. How to get div data on runtime ? Please help.