对于文本框中的Int32，值太大或太小

Question

I am getting error on this int b = Convert.ToInt32(qty.Text); if i type more than 11 numbers in quantity textbox

if (Item_Name.Text == dr["Item_Name"].ToString() && Item_Code.Text == dr["Item_Code"].ToString())
                {
                    int a = Convert.ToInt32(dr["Selling_Price"].ToString());
                    if (qty.Text == "")
                    {
                        Selling_Price.Text = "";
                    }
                    else
                    {
                        int b = Convert.ToInt32(qty.Text); //Error On This Line
                        int c = a * b;
                        Selling_Price.Text = c.ToString();
                    }
                }

Answer 1

You're getting that exception because an integer cannot store a number that large .

Int32.MaxValue Field : The value of this constant is 2147483647

Switching to a long should solve the problem for you. When you're dealing with numbers that represent money, you might want to consider using decimal too.

if (Item_Name.Text == dr["Item_Name"].ToString() && Item_Code.Text == dr["Item_Code"].ToString())
{
    int price = Convert.ToInt32(dr["Selling_Price"].ToString());
    if (qty.Text == "")
    {
        Selling_Price.Text = "";
    }
    else
    {
        long quantity = Convert.ToInt64(qty.Text);
        long total = price * quantity;
        Selling_Price.Text = total.ToString();
    }
}