在文本框中添加一个值，并在C＃中添加标签

Question

I've been trying to add a value in textbox and a label. the value inside label is automatically generated during page load..it can be negative, positive or zero (decimal too). When I'm trying to add it with the textbox value I get the following error. Below is the error and code.

Input string was not in a correct format. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.FormatException: Input string was not in a correct format

SqlCommand cmd6 = new SqlCommand("update dues set amount = @due where person='rahul'", con);
            cmd6.Parameters.Add("@due", SqlDbType.Int);
            cmd6.Parameters["@due"].Value = int.Parse(txt_rahul.Text + lbl_rahul.Text);
            cmd6.ExecuteNonQuery();

Answer 1

try this

SqlCommand cmd6 = new SqlCommand("update dues set amount = @due where person='rahul'", con);
            cmd6.Parameters.Add("@due", SqlDbType.Int);
            cmd6.Parameters["@due"].Value = Convert.ToDouble(txt_rahul.Text) + Convert.ToDouble(lbl_rahul.Text);
            cmd6.ExecuteNonQuery();

Answer 2

txt_rahul.Text + lbl_rahul.Text would concatenate the string 's together, it wouldn't add them up.

You would need to parse each one into an integer first. As in:

int something = int.Parse(txt_rahul.Text);
int somethingElse = int.Parse(lbl_rahul.Text);
cmd6.Parameters["@due"].Value = something + somethingElse;