Input string was not in a correct format in double.Parse

Question

I am new to C#. I\'m trying to make a calculator, but the following error occurred:

Input string was not in a correct format.

T

Answer 1

Your code seems hard to understand whats the use of button_13 and button_14;

I will assume your trying to do this:

bool ifNew = true;
double num1 ,num2,result;
private void Add_Click(object sender, EventArgs e))
{
   if(ifNew)
   {

    num1 =  Convert.ToDouble(textBox1.Text);
    textbox1.Clear();
    ifNew = false;
    result += num1;

   }
   else
   {
    num2 = Convert.ToDouble(textBox1.Text);
    textbox1.Clear();
    result += num2;
    num1 = 0D;
    num2 = 0D;
    ifNew = true;
   } 


}

private void Equals_Click(object sender, EventArgs e)
{
   textboxl.Text = string.Format("{0:N}",result);
}

Or you could use Double.Parse in my Convert.ToDouble It depends on your operation but I am visualizing how to do add operation you can change and edit this depends on your operation