private void equal_Click(object sender, EventArgs e) //点击等于 { if (isEqual == true) { textBox1.Text = "0"; return; } isEqual = true; str = textBox1.Text; String str1 = new Calculate().calculating(str); if (m_ && str1 != null && !str.Equals("错误")) //读入计算后的存储数据 { memory = new string(str1.ToCharArray()); m_ = false; } if (str.Equals("错误")) { error.Visible = true; str = ""; } else { str = str1; } textBox1.Text = str; }