C#文本框输入控制

C#文本框输入限制

//只能输入数字和小数点和退格键

    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (((int)e.KeyChar < 48 || (int)e.KeyChar > 57) && (int)e.KeyChar != 8 && (int)e.KeyChar != 46)
        {
            e.Handled = true;
        }
    }
    //只能输入数字和退格键
    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {

        if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar != (char)8)
        {
            e.Handled = true;
        }
    }
    //限制输入只能为数字
    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar != (Char)8)
        {
            e.Handled = true;
        }
    }

    //限制输入不能为中文和全角
    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {
        int chfrom = Convert.ToInt32("4e00", 16);    //范围（0x4e00～0x9fa5）转换成int（chfrom～chend）
        int chend = Convert.ToInt32("9fa5", 16);
        if (e.KeyChar >= (Char)chfrom && e.KeyChar <= (Char)chend)
        {
            e.Handled = true;
        }
        if (e.KeyChar >= (Char)65281 & (int)e.KeyChar <= (Char)65374)
        {
            e.Handled = true;
        }
    }
    //限制输入只能输入数字和字母，退格键
    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {
        if ((e.KeyChar >= 'a' && e.KeyChar <= 'z') || (e.KeyChar >= 'A' && e.KeyChar <= 'Z')
            || (e.KeyChar >= '0' && e.KeyChar <= '9') || (e.KeyChar == 8))
        {
            e.Handled = false;
        }
        else
        {
            e.Handled = true;
        }
    }

    //只能输入中文汉字
    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {
        System.Text.RegularExpressions.Regex rg = new System.Text.RegularExpressions.Regex("^[\u4e00-\u9fa5]$");
        if (!rg.IsMatch(e.KeyChar.ToString()) && e.KeyChar != '\b') //'\b'是退格键
        {
            e.Handled = true;
        }
    }
    //判定是否是邮箱格式
    public bool IsEmail(string value)
    {
        return System.Text.RegularExpressions.Regex.IsMatch(value, @"\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*");
    }