hi every one!
I have a datagridview which contain 5 column (data source is a table in ms acces). i want to add 3rd and 4th column using loop
but there is an error occured "input string was not in correct format"

for (int i = 0; i < dataGridView1.Rows.Count - 1; i++)    //loop to add the total and from column
{string StartTime = dataGridView1.Rows[i].Cells[3].Value.ToString();
 string Total = dataGridView1.Rows[i].Cells[2].Value.ToString();
TimeSpan spantotal = TimeSpan.Parse(Total); //convert f into timespan and store in a
 TimeSpan spanStartTime = TimeSpan.Parse(StartTime);
TimeSpan SpanEndTime = (spantotal.Add(spanStartTime));// sum of timespan a and b store in c
 TimeEnd = new DateTime(SpanEndTime.Ticks);
 string strTimeEnd = TimeEnd.ToString("hh:mm tt");
dataGridView1.Rows[i].Cells[4].Value = strTimeEnd;   //assign c to to.value
dataGridView1.Rows[i + 1].Cells[3].Value = dataGridView1.Rows[i].Cells[4].Value;//assign to.cell0.value to from.cell1.value
Comments
Same question twice?

The error is in this line

TimeSpan spantotal = TimeSpan.Parse(Total);

Well the error says clearly that the variable Total is not in the correct format. This could only mean that dataGridView1.Rows.Cells[2].Value does not contain something that can be parsed to a TimeSpan. Have you done a debug already?

dataGridView1.Rows.Cells[2].Value already contain a value
(11:10) but when later i see this value using messageBox it look like (06/10/2010 11:10:00 AM)
while i have set the default cell format usin this code

dataGridView1.Columns[2].DefaultCellStyle.Format = "hh:mm";

>DefaultCellStyle.Format = "hh:mm";
if you had done
DefaultCellStyle.Format = "d"; you would have got 6. Underneath there is always the full blown DateTime structure.
But have you already set a breakpoint and run your program so it would stop there so you could see what all the values of the variables are?

DataGrid cell return vaalue of DateTime datatype.

You may use

... 
 DateTime date = DateTime.Parse(total);
 TimeSpan ts = date.TimeOfDay;
 ..

or

TimeSpan ts=((DateTime)dataGridView1.Rows[i].Cells[2].Value).TimeOfDay;

Thank You Sir!
This solved my problem. But now i want to extract the day from the time which is the result of addition of two time.

TimeSpan spantotaltime = ((DateTime)dataGridView1.Rows[i].Cells[2].Value).TimeOfDay;
TimeSpan spanFromTime = ((DateTime)dataGridView1.Rows[i].Cells[3].Value).TimeOfDay;
 TimeSpan spanToTime = spantotaltime.Add(spanFromTime);

I want to get the day of spanToTimewhich must vary when i add the nest timespan and so on..
Once again thank You So Much

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