I am having three text boxes as below

Question

i am having three text boxes as below

Rent textbox

service tax textbox

Gross rent textbox

i am adding rent and serice tax output will be displayed in gross rent.

i write caluation code in txt_tax as below

private void txt_tax_TextChanged(object sender, EventArgs e)

{

int a, b, c;

a = Convert.ToInt32(txt_rent.Text);

b = Convert.ToInt32(txt_tax.Text);

c = a + b;

txt_grossrent.Text = c.ToString();

}

for example i type service tax amount as 1000 then i clear the 1000 amount

the error occurs as Input string was not in a correct format.

please help me.please give the correct code.

Regards

Narsiman

Vulpes · Answer

Yes int.TryParse would be better here as you can then pinpoint errors and ask the user to make an alteration. You can also check for negative values at the same time: Try: private void txt_tax_TextChanged(object sender EventArgs e) { int a b c; if (!int.TryParse(txt_rent.Text out a) || a { MessageBox.Show(Not a valid number. Please reenter.); txt_rent.Focus(); return; } if (!int.TryParse(txt_tax.Text out b) || b { MessageBox.Show(Not a valid number. Please reenter.); txt_tax.Focus(); return; } c = a + b; txt_grossrent.Text = c.ToString(); }

Muralidharan Deenathayalan · Answer

int abc=0; if (!string.IsNullOrEmpty(txt_rent.Text)) a = Convert.ToInt32(txt_rent.Text); if (!string.IsNullOrEmpty(txt_tax.Text)) b = Convert.ToInt32(txt_tax.Text); c= a+b; txt_grossrent.Text =Convert.ToString(c); Please try this code. Before doing the Convert.ToInt32 check the value of input. whether it is null or empty. Otherwise you can use Int.tryparse method also for Convert.ToInt32 function.