如何从文本框删除? [英] how to delet from textbox ?

问题描述

如果在第8个字符输入框时文本框中有7个字符，我想删除previos字符.文本框的最大长度?
Textbox1.MaxLength = 7;
这样，将不允许用户键入超过7个字符.

处理TextBox.KeyPress事件.
如果发生这种情况，请检查现有文本，并在必要时进行修改.

private void myTextBox_KeyPress(object sender, KeyPressEventArgs e)
    {
    TextBox tb = sender as TextBox;
    if (tb != null)
        {
        string existing = tb.Text;
        if (existing.Length >= 7)
            {
            tb.Text = existing.Substring(existing.Length - 6);
            tb.SelectionStart = tb.Text.Length;
            }
        }
    }

我想您想删除所有之前的7个字符，可以使用波纹管

 如果(textBox1.Text.Length >   0 ， 7 );
   textBox1.SelectionStart = textBox1.Text.Length;
} 

if there is 7 char in text box when the 8th one is enetered i want to delete the previos chars

解决方案

Instead of doing that, why not set the maximum length of the textbox?
Textbox1.MaxLength = 7;
That way, the user will not be allowed to key in more than 7 characters.

Handle the TextBox.KeyPress event.
In the event, check the existing text, and modify if necessary.

private void myTextBox_KeyPress(object sender, KeyPressEventArgs e)
    {
    TextBox tb = sender as TextBox;
    if (tb != null)
        {
        string existing = tb.Text;
        if (existing.Length >= 7)
            {
            tb.Text = existing.Substring(existing.Length - 6);
            tb.SelectionStart = tb.Text.Length;
            }
        }
    }

I think you want to remove all previous 7 chars, you can use bellow

if (textBox1.Text.Length > 7)
{
   textBox1.Text = textBox1.Text.Remove(0, 7);
   textBox1.SelectionStart = textBox1.Text.Length;
}

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