input String was not in a correct format

Question

1.00/5 (1 vote)

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I am using Windows Form Application VS2012
i Have to combobx
name
cbHadithBook
cbBaab

now i am binding it using 3 tier

C#

private void HadithBook() 
        {
            cbHadithBook.DataSource = objSearch.SelectHadithBookName();
            cbHadithBook.DisplayMember = "Book_English_Name";
            cbHadithBook.ValueMember = "Book_Id";
           //dgvHadith.DataSource = objSearch.SelectHadithText(objSearch.HadithBookNo, 1);
        }
private void HadithBaab()
        {
           
            
                MessageBox.Show("NO value selected");
            
                objSearch.HadithBookNo = Convert.ToInt32(cbHadithBook.SelectedValue.ToString());
                cbBaab.DataSource = objSearch.SelectHadithBaabEnglish();
                if (cbLanguage.SelectedIndex == 0 || cbLanguage.SelectedIndex == 1)
                {
                    cbBaab.DisplayMember = "Baab_Urdu_Name";
                }
                else if (cbLanguage.SelectedIndex == 2)
                {
                    cbBaab.DisplayMember = "Baab_English_Name";

                }
                cbBaab.ValueMember = "Baab_Id";

               //here Error input String was not in a correct format
 objSearch.Baab_Id = Convert.ToInt32(cbBaab.SelectedValue.ToString());

                dgvhadiths.DataSource = objSearch.SelectHadithText(objSearch.HadithBookNo, objSearch.Baab_Id);
            }
            
//calling above function here on form Load event
       private void Form1_Load(object sender, EventArgs e)
        {

            //cbLanguage.SelectedIndex = 2;
            cbHadithBook.SelectedValue = 1;
            cbBaab.SelectedValue = 1;
            HadithBook();
            HadithBaab();
}

Posted 16-Oct-13 18:06pm

Muhamad Faizan Khan

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Comments

Sergey Alexandrovich Kryukov 17-Oct-13 0:37am

1) In what line? 2) what's the use if you don't show the string? If you don't know what it is, find out using the debugger. Before you do it, the question is not very answerable.
Maybe, this is
objSearch.HadithBookNo = Convert.ToInt32(cbHadithBook.SelectedValue.ToString());.
If so, tell us what's in cbHadithBook.SelectedValue.ToString(), or the other string which causes the problem. Then we will gladly help you.
—SA

Muhamad Faizan Khan 17-Oct-13 0:40am

thanks

//here Error input String was not in a correct format
objSearch.Baab_Id = Convert.ToInt32(cbBaab.SelectedValue.ToString());

interger value in comboxbox's vlaue member

Muhamad Faizan Khan 17-Oct-13 0:43am

objSearch.HadithBookNo = Convert.ToInt32(cbHadithBook.SelectedValue.ToString());
same error also here

interger value in comboxbox's vlaue member

Sergey Alexandrovich Kryukov 17-Oct-13 0:45am

Use Solution 2. Avoid using Convert (in most cases; there are cases when it's needed, but they are pretty rare)...
—SA

4 solutions

Solution 4

Try this..hope so it will help you

objSearch.Baab_Id = Convert.ToInt32(cbBaab.SelectedIndex.ToString());

Posted 16-Oct-13 19:01pm

indrajeet jadhav

Comments

Muhamad Faizan Khan 17-Oct-13 1:07am

i dont want to show gridview result on basis of combobox index number

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CodeBlack · Accepted Answer · 2013-10-16T18:23:00

Solution 1

the line where you are facing error :

C#

objSearch.Baab_Id = Convert.ToInt32(cbBaab.SelectedValue.ToString());

Update above line as mentioned below :

C#

int baabValue;

            if (int.TryParse(cbBaab.SelectedValue, out baabValue))
            {
                objSearch.Baab_Id = Convert.ToInt32(cbBaab.SelectedValue.ToString());
            }

Posted 16-Oct-13 18:23pm

CodeBlack

Updated 16-Oct-13 18:24pm

v2

Comments

Muhamad Faizan Khan 17-Oct-13 0:27am

error the best overladed method match for int.TryParse(string, out int)
has some invalied argument
arguement 1: cannot covert from object to string

CodeBlack 17-Oct-13 0:31am

Update if condition as mentioned below :
if (int.TryParse(cbBaab.SelectedValue, out baabValue))

Muhamad Faizan Khan 17-Oct-13 0:35am

sir error as i told you above
error the best overladed method match for int.TryParse(string, out int)

CodeBlack 17-Oct-13 0:39am

my bad. sorry.

update if condition as below :
if (int.TryParse(cbBaab.SelectedValue.ToString(), out baabValue))

Muhamad Faizan Khan 17-Oct-13 0:46am

thank you but another error
on the same line
object reference not set to an instance of an object

CodeBlack 17-Oct-13 0:48am

what value you are getting in cbBaab.SelectedValue

Muhamad Faizan Khan 17-Oct-13 1:08am

nothing i guess empty i dont know why while i am using this in load event
cbHadithBook.SelectedValue = 1;
//cbBaab.SelectedValue = 1;

CodeBlack 17-Oct-13 1:24am

I think you are getting null value. check null condition.
if (cbBaab.SelectedValue != null && int.TryParse(cbBaab.SelectedValue.ToString(), out baabValue))

Abhinav S · Accepted Answer · 2013-10-16T18:24:00

Solution 2

Check if your text is actually a number before converting it to int.
Use Int.TryParse.

Posted 16-Oct-13 18:24pm

Abhinav S

Comments

Muhamad Faizan Khan 17-Oct-13 0:28am

on combox value memeber it is integer value. now what to do use int.tryparse?

Sergey Alexandrovich Kryukov 17-Oct-13 0:43am

Of course, a 5.
—SA

Muhamad Faizan Khan 17-Oct-13 0:49am

i used this
if (int.TryParse(cbBaab.SelectedValue.ToString(), out baabValue))
{
objSearch.Baab_Id = Convert.ToInt32(cbBaab.SelectedValue.ToString());
}
and got another error
null refrence exception

Sergey Alexandrovich Kryukov 17-Oct-13 0:56am

All right, then please see Solution 3.
—SA

Abhinav S 17-Oct-13 1:37am

Thank you SA.

Sergey Alexandrovich Kryukov · Accepted Answer · 2013-10-16T18:56:00

Muhamad Faizan Khan wrote:
…and got another error null reference exception…

I'm afraid to say you ignored my most essential advice: to use the debugger, which you should have done in first place. You really need to learn how to deal with such simple debugging by yourself, because it's absolutely impossible to look for help in all such cases.

You did not show where the exception with the message "Object reference not set to an instance of an object" is thrown.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: either make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.

Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].

Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:
http://msdn.microsoft.com/en-us/library/system.exception.aspx[^],
http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx[^].

The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx[^].

Good luck,

—SA