VB..net code error free but same C# code gives error?

I have converted my project from VB.net to C# using converter sw
Now i m facing some errors , which i try to remove
Here is the code in c# and vb.net also
But main thing is that it does not give error in vb.net
error is ,Error:- Use of unassingned local varialble "tmpYear"

        public void cmdSearch_Click(System.Object sender, System.EventArgs e)
        {
            try
            {
                frmStudentSearch dlgStudentSearch = new frmStudentSearch();
                int iStudentID;
                string strCboSelection;
                DataTable tmpDataTable;
                string strSQL;
                DataTable tmpYear;
                DataTable tmpData;
                DataTable tmpCboDataTable;

                dlgStudentSearch.ShowForm();
                //MsgBox("Student Fees" + vbCrLf + "iStudentID :: " + _CConstant._iStudentID.ToString)
                iStudentID = modMain._CConstant._iStudentID;
                if (iStudentID > 0)
                {
                    strCboSelection = "SELECT ID, Name FROM tblStudent";
                    tmpCboDataTable = modMain._CDatabase.GetDataTable(strCboSelection);
                    CboStudentName.SelectedValue = iStudentID.ToString();

                    if (CboStudentName.Text.Trim().Length != 0)
                    {
                        strSQL = "SELECT BatchID FROM tblStudent ";
                        strSQL += "WHERE ID = " + CboStudentName.SelectedValue.ToString() + " ";
                        tmpYear = modMain._CDatabase.GetDataTable(strSQL);
                        if (tmpYear.Rows.Count > 0)
                        {
                            if (Information.IsDBNull(tmpYear.Rows[0]["BatchID"]) == true)
                            {
                                Interaction.MsgBox("Batch Not Present For This Student", MsgBoxStyle.Information, null);
                                cmdSave.Enabled = false;
                                return;
                            }
                            else
                            {
                                cmdSave.Enabled = true;
                            }
                        }
                    }

                    strSQL = "SELECT ClassID,SectionID FROM tblStudentDetail ";
                    strSQL += "WHERE StudentID = " + CboStudentName.SelectedValue.ToString() + " ";
                    strSQL += "AND OrganizationID = " + modMain._CVariable._ORGANIZATIONID.ToString() + " ";
                    tmpDataTable = modMain._CDatabase.GetDataTable(strSQL);
                    if (tmpDataTable.Rows.Count == 0)
                    {
                        Interaction.MsgBox("No Student Details Present For This Student", MsgBoxStyle.Information, null);
                        cmdSave.Enabled = false;
                        return;
                    }
                    else
                    {
                        cmdSave.Enabled = true;
                    }

                    if (cmdSave.Enabled == true)
                    {
                        strSQL = "SELECT Amount FROM tblLibraryStaticFees ";
                        strSQL += "WHERE BatchID = " + tmpYear.Rows[0]["BatchID"].ToString() + " ";
//In the above line of code it says that ,Error:- Use of unassingned local varialble "tmpYear"
                        strSQL += "AND ClassID = " + tmpDataTable.Rows[0]["ClassID"].ToString() + " ";
                        strSQL += "AND SectionID = " + tmpDataTable.Rows[0]["SectionID"].ToString() + " ";
                        strSQL += "AND OrganizationID = " + modMain._CVariable._ORGANIZATIONID.ToString() + " ";

                        tmpData = modMain._CDatabase.GetDataTable(strSQL);
                        if (tmpData.Rows.Count > 0)
                        {
                            txtRegAmount.Text = (string) (tmpData.Rows[0]["Amount"]);
                        }
                        else
                        {
                            txtRegAmount.Text = "0";
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                LibraryManagement.CError.ShowError(ex, true, false.ToString(), "");
            }
        }

Code in VB.net in which no error
Private Sub cmdSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSearch.Click
        Try
            Dim dlgStudentSearch As New frmStudentSearch
            Dim iStudentID As Int32
            Dim strCboSelection As String
            Dim tmpDataTable As DataTable
            Dim strSQL As String
            Dim tmpYear As DataTable
            Dim tmpData As DataTable
            Dim tmpCboDataTable As DataTable

            dlgStudentSearch.ShowForm()
            'MsgBox("Student Fees" + vbCrLf + "iStudentID :: " + _CConstant._iStudentID.ToString)
            iStudentID = _CConstant._iStudentID
            If iStudentID > 0 Then
                strCboSelection = "SELECT ID, Name FROM tblStudent"
                tmpCboDataTable = _CDatabase.GetDataTable(strCboSelection)
                CboStudentName.SelectedValue = iStudentID.ToString

                If Len(Trim(CboStudentName.Text)) <> 0 Then
                    strSQL = "SELECT BatchID FROM tblStudent "
                    strSQL += "WHERE ID = " + CboStudentName.SelectedValue.ToString + " "
                    tmpYear = _CDatabase.GetDataTable(strSQL)
                    If tmpYear.Rows.Count > 0 Then
                        If IsDBNull(tmpYear.Rows(0).Item("BatchID")) = True Then
                            MsgBox("Batch Not Present For This Student", MsgBoxStyle.Information)
                            cmdSave.Enabled = False
                            Exit Sub
                        Else
                            cmdSave.Enabled = True
                        End If
                    End If
                End If

                strSQL = "SELECT ClassID,SectionID FROM tblStudentDetail "
                strSQL += "WHERE StudentID = " + CboStudentName.SelectedValue.ToString + " "
                strSQL += "AND OrganizationID = " + _CVariable._ORGANIZATIONID.ToString + " "
                tmpDataTable = _CDatabase.GetDataTable(strSQL)
                If tmpDataTable.Rows.Count = 0 Then
                    MsgBox("No Student Details Present For This Student", MsgBoxStyle.Information)
                    cmdSave.Enabled = False
                    Exit Sub
                Else
                    cmdSave.Enabled = True
                End If

                If cmdSave.Enabled = True Then
                    strSQL = "SELECT Amount FROM tblLibraryStaticFees "
                    strSQL += "WHERE BatchID = " + tmpYear.Rows(0).Item("BatchID").ToString + " "
                    strSQL += "AND ClassID = " + tmpDataTable.Rows(0).Item("ClassID").ToString + " "
                    strSQL += "AND SectionID = " + tmpDataTable.Rows(0).Item("SectionID").ToString + " "
                    strSQL += "AND OrganizationID = " + _CVariable._ORGANIZATIONID.ToString + " "

                    tmpData = _CDatabase.GetDataTable(strSQL)
                    If tmpData.Rows.Count > 0 Then
                        txtRegAmount.Text = tmpData.Rows(0).Item("Amount")
                    Else
                        txtRegAmount.Text = 0
                    End If
                End If
            End If
        Catch ex As Exception
            CError.ShowError(ex, True, False)
        End Try
    End Sub

So what is doing wrong in c# code?

8 Replies

Know the answer? Post it — somebody with the same question will find it here.

Suthish Nair16y ago
Accepted answer
Vikas,

Rebuid your website, check the Error List + Warnings tab.. you will get the list of all unassigned variables. These types of issues occurs when you migrate old ones to new versions. Old versions of VS did not helped us to find this types of warnings or errors. Thanks to advanced VS versions.
The better you know your coding, the better your application performance.
about int object, it has a default value of zero (0) -
for more reading refer msdn: http://msdn.microsoft.com/en-us/library/83fhsxwc(vs.71).aspx
yes i agree with Sam..
Also there is good article by Jaish Mathews, readon:
http://www.c-sharpcorner.com/UploadFile/jaishmathews/WorkingofReferenceTypeandValueType09102006022502AM/WorkingofReferenceTypeandValueType.aspx
Sam Hobbs16y ago
The best way to solve it is to read a book about the fundamentals of the languages.

Vikas Ahlawat16y ago

Hi Sam
My this problem is solved by using

DataTable tmpYear = new DataTable();

but in other coding part there are some integers which are decalare but assign a value under if 
and used outside if
then they gives same error
how solve it

Sam Hobbs16y ago
The error message says "unassingned local varialble" and that is exactly what the problem is. Look at the code; tmpYear is assigned only if both of the following are true:
- CboStudentName.Text.Trim().Length is not 0
- iStudentID > 0
Correct?
Gomathi Palaniswamy: Why not explain what the problem is of you think it is different from that?
Vikas Ahlawat16y ago
Hi Suthish Nair
you r right
But what can i do with
int iStudentid;
Gomathi Palaniswamy16y ago
Hi friend,

The data table can be initiated with out any value.I think that will not be the error here.
Sam Hobbs16y ago
The problem is with VB, not C#. It is possible for tmpYear to be used in either version without being initialized, but C# is better at detecting that.
Suthish Nair16y ago
You need to be explicit here:
```
DataTable tmpYear = null;
or
DataTable tmpYear = new DataTable();
```