private void button2_Click(object sender, EventArgs e) { TestLib c = new TestLib(); //if (text_chang_flag == null) // text_chang_flag = TextIn.Text; //else //{ // flag = string.Compare(text_chang_flag, TextIn.Text); // if (flag != 0) // text_tmp = TextIn.Text; //} if (text_tmp == null) { text_tmp = TextIn.Text; } else { text_tmp = c.Big2Low(text_tmp); } TextOut.Text = text_tmp; }