Question

I am developing an application, in which there is a button in search box (like one in itunes).
I want to enable cancel button whenever there is text in text box and disable it when text box is empty.
I tried with text_changed event on textbox with the following code, but it jump over the if condition. Even sender sends me correct values but i am unable to put it into if else.

private void textBox1_TextChanged(object sender, EventArgs e)
    {
        if (string.IsNullOrEmpty(sender.ToString()))
        {
            btn_cancel.Visible = false;
        }
        else
        {
            btn_cancel.Visible = true;
        }
    }

Please help

Answer 1

Here is a simple solution.

    private void textBox1_TextChanged(object sender, EventArgs e)
    {
        this.button1.Enabled = !string.IsNullOrWhiteSpace(this.textBox1.Text);
    }

Of course, you’ll have to set the button.Enabled = false when the form initially loads since the textbox event won’t fire on startup (true for all answers currently provided for your question).