實現如圖所示登入介面，當輸入正確使用者名稱及密碼時，轉到主介面，否則給出錯誤提示。要求不同身份的登陸者擁有不同的操作許可權。

原始碼：

1.初始化三個string型別的變數分別用來儲存使用者名稱、密碼和身份。

string yhm, mm, sf;

private void Form1_Load(object sender, EventArgs e)
        {
            yhm=mm="";
            sf=radioButton1.Text;
        }

1>學生：

private void radioButton1_CheckedChanged(object sender, EventArgs e)
        {
            if(radioButton1.Checked)
            {
                sf=radioButton1.Text;
                checkBox1.Checked = true;
                checkBox2.Checked=checkBox3.Checked=checkBox4.Checked=checkBox5.Checked=false;
            }
        
        }
 

 private void radioButton2_CheckedChanged(object sender, EventArgs e)
        {
            if (radioButton2.Checked)
            {
                sf = radioButton2.Text;
                checkBox1.Checked=checkBox2.Checked = true;
                checkBox3.Checked = checkBox4.Checked = checkBox5.Checked = false;
            }
        
        }
 

3>管理員：

private void radioButton3_CheckedChanged(object sender, EventArgs e)
        {
            if (radioButton3.Checked)
            {
                sf = radioButton3.Text;
                checkBox1.Checked = checkBox2.Checked = checkBox3.Checked = checkBox4.Checked = checkBox5.Checked = true;
            }
        
        }

1>確定：

 private void button1_Click(object sender, EventArgs e)
        {
            yhm = textBox1.Text.Trim();
            mm = textBox2.Text.Trim();
            if (yhm == "xs" && mm == "xs" && sf == "學生")
            {
                tabControl1.SelectedTab = tabPage2;
                panel2.Visible = true;
                button4.Enabled = button5.Enabled = button6.Enabled = button7.Enabled = false;
                panel1.Visible = false;
            }


            else if (yhm == "js" && mm == "js" && sf == "教師")
            {
                tabControl1.SelectedTab = tabPage2;
                panel2.Visible = true;
                button3.Enabled=button4.Enabled = true;
                button5.Enabled = button6.Enabled = button7.Enabled = false;
                panel1.Visible = false;
            }

            else if (yhm == "gly" && mm == "gly" && sf == "管理員")
            {
                tabControl1.SelectedTab = tabPage2;
                panel2.Visible = true;
                button3.Enabled=button4.Enabled = button5.Enabled = button6.Enabled = button7.Enabled = true;
                panel1.Visible = false;
            }

            else
                MessageBox.Show("使用者名稱或密碼錯誤","登入失敗");
        }

2>取消：

private void button2_Click(object sender, EventArgs e)
        {
            this.Close();
        }

3>登出登入：

private void button8_Click(object sender, EventArgs e)
        {
            panel1.Visible = true;
            panel2.Visible = false;
            textBox1.Text = textBox2.Text = "";
            radioButton1.Checked = true;
            tabControl1.SelectedTab = tabPage1;
        }

4>退出系統：

private void button9_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }