need some help in creating classes

[blakdeath]

I'm new to OOP
what I'm trying to do is use the naive bayesian alogrithm on the iris database
each flower has 5 attributes:
sepal length, width, petal length & width and the flowertype
here's my class code so far:
public class flower
{
double slength;
double swidth;
double plength;
double pwidth;
string ftype;
}

i understand that if i declare a flower of a certain type i can access its attribute using x.slength=1.2;
what im trying to do is create an Array of flowers so i did the following:
flower[] list = new flower[90];
how can i access the 31st flowers petal length???
thanks in advance

[blakdeath]

apparently the problem was declaring the attributes as public variables
after ive done that i still cant access them and c# throws a nullvalueexception or something like that

[Ubiquitous]

How are you assigning the values to each flower? You are creating the list but how are you populating it what code are you using?

Simple example:

Flower x;
Random rnd = new Random();

// Create an empty list
List<Flower> flowers = new List<Flower>(10);

// Populate list with randomly created numbers
for (int i = 0; i < 10; i++)
{
   // Set x as a new instance for new flower
   x = new Flower();

   // Create random number and convert to string to set as name for flower
   x.ftype = rnd.Next().ToString();

  // Add the new flower to the list 
   flowers.Add(x);
}

// Write the name of all the Flower objects found in the list
foreach (Flower f in flowers)
{
   Console.WriteLine(f.ftype);
}

// Wait for user input before continuing
Console.ReadKey();

Post more of your code and I'm sure someone with more experience will chime in and help you out.

Also when you post your code use
[code]
// Place code inside
[/code]

[TheGreatCthulhu]

The indices in C# arrays, lists, and other collections are zero-based; 0 is the first elem, 1 is the second, 2 is the third... n-1 is the n-th.

To get the 31st flower, you would use an indexer:
// assuming that flowers is an array
flowers[30].plength = 1.2;

Note - this is the same as:
flower temp = flowers[30];
temp.plength = 1.2;

To iterate through the whole collection - you'd either use the foreach statement, or the for loop - Google can help you with that, as well as the answer posted by Ubiquitous.

BTW, when it comes to C# naming conventions, you would usually use PascalCasing for type names (which include classes) - that is, start each word in the name with a capital letter.

[JeffInTexas]

public Form1()
        {

            InitializeComponent();

            Flower flower1 = new Flower(1, 1, 1, 1, "Daisy");
            MessageBox.Show("flower1: \n\n FlowerType=" + flower1.FlowerType);

            // This is SETTING the value (really, re-setting).
            flower1.FlowerType="Sunflower";
            // The reference to FlowerType below is just GETTING its value.
            MessageBox.Show("flower1: \n\n FlowerType=" + flower1.FlowerType);

            Flower flower32=new Flower(4,3,2,1,"Violet")
            //  Just use the MessageBox code above, and you can substitute for flower32.
            
        }



        public class Flower
        {
                        
            public Flower(double slength, double swidth, double plength, double pwidth, string ftype)
            //  You could name the above parameters whatever you want, but just know that they are to correspond with your properties in the proper order.    
            {
                //  Here, you are saying that THIS NEW FLOWER has the values that you passed in the parameters above.
                this.SepalLength = slength;
                this.SepalWidth = swidth;
                this.PedalLength = plength;
                this.PedalWidth = pwidth;
                this.FlowerType = ftype;
            }

            //  Now you have to have set and get methods for each.
            //  You can set the property with SET.
            //  You can get the value assigned to a property with GET.
            //  A GET is where you just want the value, as in double number1=flower1.slength (you are getting the slength and assigning it to number)
            //  A SET is where you assign the value, as in flower1.slength=2.34

            //  Note:   You should name your properties better, like below.   
            //  This way, you reference by something not so ambiguous, like flower1.FlowerType
            public double SepalLength { get; set; }
                
            public double SepalWidth { get; set; }
           
            public double PedalLength { get; set; }
           
            public double PedalWidth { get; set; }
           
            public string FlowerType { get; set; }

        }