Invalid rank specifier:expected ',' or ']' error

Question

Before i asked my question, I read the previous posts.When I run the script, it shows Invalid rank specifier:expected ',' or ']' error at following code. BTW, I tried with new float[8939, 100]; but it still shows the error. And also how can use hashtable to save the result where i wrote the hashtable comments.

namespace function
{
    public partial class Form1 : Form
    {

            float userscore,itemscore,result;
            string lineitem, lineuser;
            float[][] a = new float[89395][100];          //<----the error is here
            float[][] b = new float[1143600][100];        //<----the error is here
            //float[,] c = new float[89395, 100];
            StreamReader fileitem = new StreamReader("c:\\1.txt");
            StreamReader fileuser = new StreamReader("c:\\2.txt");
        public Form1()
        {
            InitializeComponent();

             for (int x = 0; x <= 8939500; x++)
            {
                lineuser = fileuser.ReadLine();
                string[] values = lineuser.Split(' ');
                int userid, factoriduser;
                foreach (string value in values)
                {
                    userid = Convert.ToInt32(values[0]);
                    factoriduser = Convert.ToInt32(values[1]);
                    userscore = Convert.ToSingle(values[2]);
                    a[userid][factoriduser] = userscore;
                }
            }

            for (int y = 0; y <= 114360000; y++)
            {
                lineitem = fileitem.ReadLine();
                string[] valuesi = lineitem.Split(' ');
                int itemid, factoriditem;
                foreach (string value in valuesi)
                {
                    itemid = Convert.ToInt32(valuesi[0]);
                    factoriditem = Convert.ToInt32(valuesi[1]);
                    itemscore = Convert.ToSingle(valuesi[2]);
                    b[itemid][factoriditem] = itemscore;
                }

            }

        }
        public float dotproduct(int userid,int itemid)
        {

            //get the score of 100 from user and item to dotproduct
            float[] u_f = a[userid];
            float[] i_f = b[itemid];

            for (int i = 0; i <u_f.GetLength(1); i++)
            {
                result += u_f[userid] * i_f[itemid];
            }
            return result;

        }

        private void btn_recomm_Click(object sender, EventArgs e)
        {
            if(txtbx_id.Text==null)
            {
                MessageBox.Show("please insert user id");
            }
         if (txtbx_id.Text != null)
          {
           int sc = Convert.ToInt32(txtbx_id.Text);
           if (sc>=0 &&sc<=89395)
            {
              for (int z=0;z<=1143600;z++)
                {
                  dotproduct(sc,z);
                }
               //Hashtable hashtable = new Hashtable(); 
               //put the result in hashtable
               //foreach (DictionaryEntry entry in hashtable)
                 //{
                   //Console.WriteLine("{0}, {1}", entry.Key, entry.Value);
                // }
            }
         }
            if (txtbx_id==null &&txtbx_itemid==null)
            {
                int uid = Convert.ToInt32(txtbx_id.Text);
                int iid = Convert.ToInt32(txtbx_itemid.Text);
                {
                    if (uid>=0 && uid<=89395 && iid>=0 && iid<=1143600)
                    {
                        dotproduct(uid,iid);
                        MessageBox.Show("The Score of user id "+uid+" is "+result);
                    }
                }
            }
        }

Answer 1

You cannot make a new 2D array like that - you do it one dimension at a time. You can useva loop to initialize the second dimensiuon, or use LINQ:

float[][] a = Enumerable.Range(0, 89395).Select(i=>new float[100]).ToArray();

Answer 2

float[,] a = new float[89395,100];
float[,] b = new float[1143600,100];

Reference: http://msdn.microsoft.com/en-us/library/2yd9wwz4.aspx

Answer 3

You cannot declare jagged array like that. You have to declare outer array first, and then declare all inner arrays:

float[][] a = new float[89395][]; 
for(int i = 0; i < 89395; i++)
    a[i] = new float[100];

or you should change your array to multidimensional float[,] array:

float[,] a = new float[89395,100];