Question

“你可以教我如何禁用按钮，直到所有文本框都不为空。” 在我的设计表单中命名登录。我有2个文本框和2个按钮我想禁用按钮，直到所有文本框都不为空

帮助我所以我在c＃windows应用程序表单中的代码

 SqlConnection con = new SqlConnection(@"Data Source=ADMIN-\MSSQLSERVERR;Initial Catalog=Admin;Integrated Security=True");
    private void button1_Click(object sender, EventArgs e)
    {

        SqlDataAdapter sda = new SqlDataAdapter("Select USN From Admin where USN ='" + textBox1.Text + "'and Password ='" + textBox2.Text + "'", con);
        DataTable dt = new DataTable();
        sda.Fill(dt);


        if (dt.Rows.Count == 1)
        {
            this.Hide();
            Admin_Panel aa = new Admin_Panel(dt.Rows[0][0].ToString());
            aa.Show();
        }

        else 
        {
            MessageBox.Show("Please check your username and password");
            textBox1.SelectAll();
            textBox2.Text = "";
        }
        button1.Enabled = !string.IsNullOrWhiteSpace(textBox1.Text);
    }

    private void button2_Click(object sender, EventArgs e)
    {
        SqlDataAdapter sda = new SqlDataAdapter("Select USN From Admin where USN ='" + textBox1.Text + "'and Password ='" + textBox2.Text + "'", con);
        DataTable dt = new DataTable();
        sda.Fill(dt);


        if (dt.Rows.Count == 1)
        {
            this.Hide();
            Student aa = new Student(dt.Rows[0][0].ToString());
            aa.Show();
        }

        else
        {
            MessageBox.Show("Please check your username and password");
            textBox1.SelectAll();
            textBox2.Text = "";
        }


        button2.Enabled = !string.IsNullOrWhiteSpace(textBox1.Text);

    }

    private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
            e.Handled = true;
        base.OnKeyPress(e);


    }

我尝试了我所知道的一切，但它不起作用:( 我也试试这个button1.Enabled =！string.IsNullOrWhiteSpace（textBox1.Text）; 但是当我已经将USN和密码放在文本框中时，2个按钮未启用

Answer 1

首先将您的buttons.Enabled属性设置为false。然后为两个TextBox添加TextChanged-Handler，在其中检查两个TextBox是否包含某些内容。

处理程序的代码可能如下所示：

private void textBox1_TextChanged(object sender, EventArgs e)
{
    setButtonVisibility();
}

private void textBox2_TextChanged(object sender, EventArgs e)
{
    setButtonVisibility();
}

private void setButtonVisibility()
{
    if ((textBox1.Text != String.Empty) && (textBox2.Text != String.Empty))
    {
        button1.Enabled = true;
        button2.Enabled = true;
    }
    else
    {
        button1.Enabled = false;
        button2.Enabled = false;
    }
}

Answer 2

您需要在其Changed事件中监控文本框的更改，例如：

private void textbox1_Change(object sender, EventArgs e)
{
    ConditionallyEnableSubmitButton();
}

private void textbox2_Change(object sender, EventArgs e)
{
    ConditionallyEnableSubmitButton();
}

private void ConditionallyEnableSubmitButton()
{
    button1.Enabled = (!string.IsNullOrWhiteSpace(textBox1.Text) ||   
                       !string.IsNullOrWhiteSpace(textBox2.Text));
}

提示不收取任何额外费用：提供任何控件，您将以编程方式引用一个可识别的名称，例如“btnSubmit”，“txtbxUsername”，“txtbxPwd”等。

你可以做的比阅读史蒂夫麦康奈尔的“代码完整”更糟糕，因为这和其他许多方面的良好实践。

Answer 3

private void textbox1_TextChanged(object sender, EventArgs e)
{
    EnableButton();
}

private void textbox2_TextChanged(object sender, EventArgs e)
{
    EnableButton();
}

private void  EnableButton()
{
    if(textbox1.Text == "" || textbox2.Text == "")
    {
        button1.Enabled = false;
        button2.Enabled = false;
    }
    else
    {
        button1.Enabled = true;
        button2.Enabled = true;
    }
}

如何禁用提交按钮，直到c＃中的文本框不为空？

3 个答案: