"Input string was not in a correct format" error

Question

The following Script shows the

"index was outside the bounds of the array"

at line

for (int i = 0; i <u_f.GetLength(1); i++)

when I change it to

for (int i = 0; i <=u_f.GetLength(1); i++)

it shows

"Input string was not in a correct format"

error in line int uid = Convert.ToInt32(txtbx_id.Text);

        float userscore,itemscore,result;
        string lineitem, lineuser;
        //float[][] a = new float[89395][100];
        //float[][] b = new float[1143600][100];
        float[][] a = Enumerable.Range(0, 89395).Select(i => new float[100]).ToArray();
        float[][] b = Enumerable.Range(0, 1143600).Select(j => new float[100]).ToArray();
        //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();
            if (!string.IsNullOrEmpty(lineuser))
            {
                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();
            if (!string.IsNullOrEmpty(lineitem))
            {
                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++)  //<----error
        {
            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 && txtbx_itemid==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)
               {
                 System.Console.WriteLine("{0}, {1}", entry.Key, entry.Value);
               }
        }
     }
        if (txtbx_id!=null && txtbx_itemid!=null)
        {
            int uid = Convert.ToInt32(txtbx_id.Text);     //<----error
            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);
                }
            }
        }

You have a 1D array, so `.GetLength(1)` is out-of-bounds because your array only has one dimension (the argument to `GetLength` is zero-based). Use `.GetLength(0)` or better yet, just `.Length`. — Matt Burland, Feb 21 '14 at 14:37

Sudhakar Tillapudi · Accepted Answer · 2014-02-21T15:29:18.103

"index was outside the bounds of the array"

Problem 1: You are accessing the GetLength(1) elements from invalid dimension. you have only 1 dimension array but accessing second dimension Length as always Array Index starts from zero.

Solution 1: You should use GetLength(0) or Length as your array is single dimensional array.

Array.GetLength(0) returns the number of elements in the first dimension of the Array.

From MSDN:

Gets a 32-bit integer that represents the number of elements in the specified dimension of the Array.

Replace This:

for (int i = 0; i <u_f.GetLength(1); i++)

With This:

for (int i = 0; i <u_f.GetLength(0); i++)

OR With

  for (int i = 0; i <u_f.Length; i++)

Problem 2: you are doing null check for TextBox control directly but not for TextBox Text/Value. so what happens here is even if user does not enter any value in your textbox the if condition willnot fail as TextBox is not null.so it enters the if block but when it tries to convert that empty string/value into integer using following statement :

int uid = Convert.ToInt32(txtbx_id.Text);     //<----error

as you said it throws exception.

Solution 2: You need to perform null check for TextBox value like TextBox1.Text!=null

Suggestion 1: You can use String.IsNullOrWhiteSpace() method to verify wether value is Null,Empty or WhiteSpace.

Suggestion 2: if you want to avoid runtime exceptions while parsing the user input into integer, you need to use int.TryParse() method.

Replace This:

if (txtbx_id!=null && txtbx_itemid!=null)
    {
        int uid = Convert.ToInt32(txtbx_id.Text);     //<----error
        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);
            }
        }
    }

With This:

if (!String.IsNullOrWhiteSpace(txtbx_id.Text) &&      
     !String.IsNullOrWhiteSpace(txtbx_itemid.Text)) 
{
  int uid,iid;     
  if(int.TryParse(txtbx_id.Text,out uid) && int.TryParse(txtbx_itemid.Text,out iid))      
  {
    if (uid>=0 && uid<=89395 && iid>=0 && iid<=1143600)
    {
      dotproduct(uid,iid);
      MessageBox.Show("The Score of user id "+uid+" is "+result);
    }
   }
}

I would also either `TryParse` or else wrap in a try / catch block the part where you are converting a (user inputted) string to an integer. Never trust the user to actually type a number and not something else! Or even better - use a NumericUpDown control instead of a textbox. — Matt Burland, Feb 21 '14 at 15:22

Patrick Hofman · Answer 2 · 2014-02-21T14:49:02.320

1

Referring to the problem:

int uid = Convert.ToInt32(txtbx_id.Text);     //<----error

Try to use Int32.TryParse when having use input that can be different then expected:

int uid;
if (!Int32.TryParse(txtbx_id.Text, out uid))
{
    MessageBox.Show("Input is not a number! Try again!");
}

edited Feb 21 '14 at 14:49

answered Feb 21 '14 at 14:37

Patrick Hofman

153,850
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Thank you @Patrik Hofman. I don't need to use "if" here. I only wants to put the entry into the integer variable. How should I do that? – user3328039 Feb 21 '14 at 14:53
`Int32.TryParse` tries to parse the text to an `int`. If it fails, `Int32.TryParse` returns `false`. If it succeeds, it returns `true` and sets the value of `uid`. – Patrick Hofman Feb 21 '14 at 14:55
@user3328039: The `if` is just to show a message in case of problems. – Patrick Hofman Feb 21 '14 at 14:56

D Stanley · Answer 3 · 2014-02-21T15:29:41.260

Your two errors are unrelated. THe reason you're getting an error on

for (int i = 0; i < u_f.GetLength(1); i++)

is because u_f one has one dimension, but you are asking for the length of the second dimnsion (GetLength takes a 0-based dimension index).

Just use

for (int i = 0; i < u_f.Length; i++)

Your other error is caused by txtbx_id.Text not representing a valid int value.

In addition, this method is guaranteed to fail, because an array of length x does not have a value at array[x] (array[x-1] is the last item in the array):

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];  // this is GUARANTEED to fail 
    }
    return result;
}

I think you want

    for (int i = 0; i <u_f.Length; i++)  
    {
        result += u_f[i] * i_f[i];  
    }

instead.

@D Stanley, you mean I must define an array after "result += u_f[userid] * i_f[itemid];" line like: for (int i=0;i — user3328039, Feb 21 '14 at 15:28

score 0 · Answer 4 · edited May 23 '17 at 10:28

I also ran into this error when I had a single curly brace in a string (and the exception wasn't very helpful in figuring it out):

string result = string.Format("{label: '{0}, {1}', children: [", prefixLabel, prefixPointer);

---------------------------------------------------^-----------------------------

The solution in this case is doubled curly braces: {{ EG:

string result = string.Format("{{label: '{0}, {1}', children: [", prefixLabel, prefixPointer);

---------------------------------------------------^-----------------------------

I discovered that if I removed the curly brace just before the word label, the problem went away, so I Googled how to escape it. Here's the link to the original SO Question I found on escaping curly braces, and it has many more links if you need more reading.

Hopefully this helps someone else who's confused by the “Input string was not in a correct format” error when they had no integers in their string similar to my experience just now.

"Input string was not in a correct format" error

4 Answers4