Question

I am getting this error:

Error: Format Exception: Input string was not in a correct format.

at

foreach (DataRow row in dtChanges.Rows)
            {
                using (SQLiteConnection conn = new SQLiteConnection(connString))
                {
                    conn.Open();
                    SQLiteCommand upCmd = new SQLiteCommand(@"update.......",conn);
           upCmd.Parameters.AddWithValue("@Flux",float.Parse(row["Flux"].ToString()));

This row[“Flux”] is from the datagridview. It could be an “” string. I suppose this is what is causing the problem. Flux is a numeric in the DB. I am sqlite DB.
I understand this error that “” cannot be converted to a decimal. But what would be the best way to tackle this?

Stack Trace: 
       at System.Number.ParseSingle(String value, NumberStyles options, NumberFormatInfo numfmt)
       at System.Single.Parse(String s)
       at RVEST.frmVesselData.SaveData(DataGridView dgv) in C:\D_Drive_Stuff\RVESTV2\RVEST\frmVesselData.cs:line 249
       at RVEST.frmVesselData.btnSave_Click(Object sender, EventArgs e) in C:\D_Drive_Stuff\RVESTV2\RVEST\frmVesselData.cs:line 190
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at RVEST.Program.Main() in C:\RVEST\Program.cs:line 26
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()

Thank yu
Sun

Answer 1

if you’re ok with a zero, try a

float result;
result = row["flux"] != null && float.TryParse(row["flux"].ToString(), out result) ? result :0;

upCmd.Parameters.AddWithValue("@Flux", result);

Null and empty values will be converted to 0.

if you wanna get a null value :

float result;
    var res= row["flux"] != null && float.TryParse(row["flux"].ToString(), out result) ? (float?)result :null;

upCmd.Parameters.AddWithValue("@Flux", res);

In any case,

You must check :
– if row[“flux”] is null before calling “ToString()”.
– Then see if value.ToString() can be parsed to float.