c# - 允许一个“。”值c#的文本框验证

Question

我想要文本框验证只允许一个.值和一个数字。意味着我的文本框值应该只采用数字和一个.值。值应该是 123.50。我正在使用代码在我的价值结束时添加.oo或.50价值。我的代码是

double x;
double.TryParse(tb.Text, out x);
tb.Text = x.ToString(".00");

它从键盘上获取所有键，但我只想获取数字和一个.值。

Answer 1

为您的文本框添加一个Control.KeyPress事件处理程序。

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar))  //bypass control keys
    {
        int dotIndex = textBox1.Text.IndexOf('.');
        if (char.IsDigit(e.KeyChar))     //ensure it's a digit
        {   //we cannot accept another digit if
            if (dotIndex != -1 &&  //there is already a dot and
                //dot is to the left from the cursor position and
                dotIndex < textBox1.SelectionStart &&
                //there're already 2 symbols to the right from the dot
                textBox1.Text.Substring(dotIndex + 1).Length >= 2)
            {
                e.Handled = true;
            }
        }
        else //we cannot accept this char if
            e.Handled = e.KeyChar != '.' || //it's not a dot or
                        //there is already a dot in the text or
                        dotIndex != -1 ||   
                        //text is empty or
                        textBox1.Text.Length == 0 || 
                        //there are more than 2 symbols from cursor position
                        //to the end of the text
                        textBox1.SelectionStart + 2 < textBox1.Text.Length;
    }
}

您可以通过设计器或在您的构造函数中执行此操作，如下所示：

public Form1()
{
    InitializeComponent();
    //..other initialization
    textBox1.KeyPress += new KeyPressEventHandler(textBox1_KeyPress);
}

我还添加了几项检查以确保您不仅可以在文本末尾插入数字，还可以在任何位置插入数字。与点相同。它控制您从点右侧不超过 2 位数字。我使用TextBox.SelectionStart 属性来获取光标在文本框中的位置。查看此线程以获取更多信息：如何在文本框中找到光标的位置？

Answer 2

只需在 textBox 的 keyPress 事件中，您就可以这样做......

        e.Handled = !char.IsDigit(e.KeyChar)&&(e.KeyChar != '.') && !char.IsControl(e.KeyChar);
        if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1))
        {
            e.Handled = true;
        }

Answer 3

试试这个

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!char.IsControl(e.KeyChar)
               && !char.IsDigit(e.KeyChar)
               && e.KeyChar != '.')
            e.Handled = true;

        // only allow one decimal point
        if (e.KeyChar == '.'
            && textBox1.Text.IndexOf('.') > -1)
            e.Handled = true;
    }

Answer 4

试试这个代码，只需替换你想要的输入类型'validinpu'字符串。

try
{
    short charCode = (short)Strings.Asc(e.KeyChar);
    string validinput = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-0123456789 .";
    if (Strings.InStr(validamt, Conversions.ToString(Strings.Chr(charCode)), Microsoft.VisualBasic.CompareMethod.Binary) == 0)
    {
        charCode = 0;
    }
    if (charCode == 0)
    {
        e.Handled = true;
    }
}

Answer 5

另一个例子 ，

 private void txtPrice_KeyPress(object sender, KeyPressEventArgs e)
    {
         // To disallow typing in the beginning writing
        if (txtPrice.Text.Length == 0)
        {
            if (e.KeyChar == '.')
            {
                e.Handled = true;
            }
        }
        if (!char.IsDigit(e.KeyChar) && e.KeyChar != 8 && e.KeyChar != 46)
        {
            e.Handled = true;
        }
        if (e.KeyChar == '.' && txtPrice.Text.IndexOf('.') > -1)
        {
            e.Handled = true;
        }
    }

Answer 6

也试试这个短的

e.Handled = (!(e.KeyChar == (char)Keys.Back || e.KeyChar == '.')); //allow  dot and Backspace
e.Handled = (e.KeyChar == '.' && TextBox1.Text.Contains(".")); //allow only one dot

这个例子只允许一个点和退格

Answer 7

 if (textBox.Text!="")
        {
            string txt = textBox.Text;
            if (e.KeyChar.ToString().Any(Char.IsNumber) || e.KeyChar == '.')
            {
                textBox.Text = rate;
            }
            else
            {
                MessageBox.Show("Number Only", "Warning");
                textBox.Text = "";
            }
        }

我测试过的代码

Answer 8

if(e.KeyChar.Equals('\b'))
 {
  e.Handled = false;
 }
else
 if (!char.IsControl(e.KeyChar)
           && !char.IsDigit(e.KeyChar)
           && e.KeyChar != '.')
  {
        e.Handled = true;
  }
 else
    // only allow one decimal point
    if (e.KeyChar == '.'
        && textBox1.Text.IndexOf('.') > -1)
  {        
    e.Handled = true;  
  }