Windows 窗体计算器中的错误仅适用于 2 个值

Question

Error is coming in num1+float.Parse(textBox1.text); I am developing a calculator and whenever i click on number and then click on any operator the program stops saying input string was not in a correct format. I did not make any equal operator in calculator so when i will click on another value after clicking on operator it will show me the result in textox.

private void buttonAdd_Click(object sender, EventArgs e)
    {
        num1 = float.Parse(textBox1.Text);
        textBox1.Clear();
        textBox1.Focus();

        ans = num1 + float.Parse(textBox1.Text);
        textBox1.Text = ans.ToString();
    }

Answer 1

You have cleared the text box.

Obviously you do not have anything in your textbox to add.

If you want increment, the textbox value, store the value in a temporary variable first.