关键新闻事件不起作用 [英] key press event not working

问题描述

我遇到了按键事件的问题。当我在textbox1中输入10位数时，它需要10位数。但是当我清除textbox1按退格键然后再输入数字时，它只需9位数就是我的问题。请告诉我我的代码出现了什么问题，如

I have problem with keypress event. when i enter 10 digits in textbox1 it takes 10 digits as i want. but when i clear textbox1 pressing backspace and now enter digits again it takes only 9 digits that is my problem. please tell me what's going wrong with my code is given as under

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar != '\b' && textBox4.Text.Trim().Length > 9)
    {
        //here '\b' is for backspace
        e.Handled = true;
        MessageBox.Show("You can't enter more than ten digits...");
        textBox4.MaxLength = 9;
    }
}

推荐答案

在if语句中，将MaxLength设置为9，因此它只接受9个字符。您不必更改此值。

Inside your if statement, you set the MaxLength to 9, so it only accepts 9 chars. You don't have to change this value.

输入第十个数字后（ textBox4.Text.Trim（）。长度> 9 ）你设置 textBox4.MaxLength = 9;



这就是为什么第一次10工作，但在那之后只有9

Once the tenth digit is entered (textBox4.Text.Trim().Length > 9) you are setting the textBox4.MaxLength = 9;

That is why the first time 10 works, but after that only 9

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