如何知道特定文本框中是否有更改，该文本框是在C＃中动态创建的

Question

I want to put a value in other dynamically created textbox if there is a changes in a specific textbox that was also dynamically created. How could I possibly do this?

this is how i created the textbox:

for (int x = 0; x < dt.Rows.Count; x++)
        {
            TextBox txt = new TextBox();
            txt.Name = dt.Rows[x]["field_name"].ToString();
    txt.Text = txt.Name;
            txt.Width = 200;
            var margintx = txt.Margin;
            margintx.Bottom = 5;
            txt.Margin = margintx;

            flowLayoutPanelText.Controls.Add(txt);
        }

Here is the output of it:

Example if I put a value to the Mag Data, it will also pass the value to Card Number and Exp Date. How could I possibly do this?

Answer 1

You can dynamically add an event handler to your Dynamic TextBox's TextChanged Event and since you are also using your Field Names as your TextBox Name you can cast your events sender object to determine which TextBox was changed.

for (int x = 0; x < dt.Rows.Count; x++)
{
    TextBox txt = new TextBox();
    txt.TextChanged += new EventHandler(txt_TextChanged);
    txt.Name = dt.Rows[x]["field_name"].ToString();
    txt.Text = txt.Name;
    txt.Width = 200;
    var margintx = txt.Margin;
    margintx.Bottom = 5;
    txt.Margin = margintx;
    flowLayoutPanelText.Controls.Add(txt);
}

void txt_TextChanged(object sender, EventArgs e)
{
    TextBox tb = (TextBox)sender;
    if (tb.Name == "Mag Data")
    {
        //Do Stuff Here
    }
}

---

The issue that you are having is that your Name Property is not accessable as a TextBox ie you can not do "Card Number".Text you will need to search the Control Collection for the TextBox named "Card Number" you can use the Controls.Find Method to do so.

ie

if (tb.Name == "Mag Data")
{
    Control[] cntrl = Controls.Find("Card Number", true);
    if (cntrl.Length != 0)
    {
        ((TextBox)cntrl[0]).Text = tb.Text;
    }
}

Answer 2

Add an event handler to the textbox:

txt.TextChanged += (sender, args) => {
    // Logic to update other textboxes
};