如何修复TextBox中的字符长度 [英] How to fix Character Length in a TextBox

问题描述

亲爱的朋友，

如何在文本框中修复字符长度？假设我想限制为3个三个字符。它不仅应输入少于或多于三个字符。其次，我想只允许文本框中的文本。请帮帮我。

解决方案

1.要限制三个字符的文本框的最大长度，写一下

< asp：TextBox ID =TextBox1runat =serverMaxLength =3>< / asp：TextBox> 

2.在文本框中正好匹配三个字符添加以下javascript函数

  function  checkLength（obj）{
  if （obj.value.length！=  3 ） {
 alert（ 应该是三个char。）; 
 obj.focus（）; 
} 
} 

并在onblur活动中调用该函数

 TextBox1.Attributes.Add（onblur，checkLength（this））; 

3.仅允许文本框中的文本添加以下javascript函数

  function  handleKeydown（event）{
 keyEntry = event .keyCode || event.which; 
  if （
（（keyEntry> = '  65'）&&（keyEntry< = '  90'））|| 
（（keyEntry> = '  97'）& &（keyEntry< = '  122'））|| 
（keyEntry == '  46'）|| 
（keyEntry == '  32'）|| 
 keyEntry == '  45' || 
 keyEntry == '  46'  || 
 keyEntry == '  8' || 
 keyEntry == '  35' || 
 keyEntry == '  36' || 
 keyEntry == '  9'）
 返回  true ; 
  else  
  return   false < /跨度>; 
} 

并添加onkeydown&代码背后的onpaste处理程序

 TextBox1.Attributes.Add（onkeydown，return handleKeydown（event））; 
 TextBox1.Attributes.Add（onpaste，return handleKeydown（event））; 

希望这会对你有帮助。

touseef4pk写道：

说我想限制为3个三个字符。它不仅应该输入少于或多于三个字符。

有很多方法：

1）使用Javascript - 编写文本框的代码onblur来检查长度是否等于3。

 <   asp：TextBox     ID   =  TextBox1    runat   =  server    onblur   =  javascript：validate（ ）; >  <   / asp：TextBox  >  

  function  validate（）
 {
  if （ document  .getElementById（  TextBox1）。value.length！=  3 ）
 {
 alert（  text lenghth必须为3）; 
  document  .getElementById（  TextBox1< /跨度>）选择（）; 
  document  .getElementById（  TextBox1< /跨度>）聚焦（）; 
  return   false ; 
} 
 其他 
 {
 返回 真; 
} 
} 

2）使用 RegularExpressionValidator 。你需要写一个正则表达式来检查输入的值是3个字符。

touseef4pk写道：

请告诉我如何编写reqular表达式来限制文本框中最多三个字符的字符

试试这个：\ b [a-zA-Z] {3} \b



[/编辑]

touseef4pk写道：

我想只允许文本框中的文字。

文本是指字母数字，这是文本框的默认值。

我猜你不是那个意思。请澄清。

感谢您的回复。请告诉我如何编写reqular表达式来限制文本框中最多三个字符的字符。 Actualy我的意思是说输入shoule只是字母，只有The。它不应该接受数值。请帮我解决这个冲突。

Dear fellow,
How can I fix character length in textbox? Say i want to restrict to 3 three characters. It should not only to enter less than or more than three characters. And secondly, I want to allow only text in the textbox. Please help me out.

解决方案

1.To restrict maxlength of textbox with three character, write

<asp:TextBox ID="TextBox1" runat="server" MaxLength="3"></asp:TextBox>

2.To match exactly three character in textbox add following javascript function

function checkLength(obj) {
            if (obj.value.length != 3) {
                alert("Should be exactly three char.");
                obj.focus();
            }
        }

And call the function in onblur event

TextBox1.Attributes.Add("onblur", "checkLength(this)");

3.To allow only text in textbox add following javascript function

function handleKeydown(event) {
            keyEntry = event.keyCode || event.which;
            if (
                ((keyEntry >= '65') && (keyEntry <= '90')) ||
                ((keyEntry >= '97') && (keyEntry <= '122')) ||
                (keyEntry == '46') ||
                (keyEntry == '32') ||
                keyEntry == '45' ||
                keyEntry == '46' ||
                keyEntry == '8' ||
                keyEntry == '35' ||
                keyEntry == '36'||
                keyEntry == '9')
                return true;
            else
                return false;
        }

And add onkeydown & onpaste handler in code behind

TextBox1.Attributes.Add("onkeydown", "return handleKeydown(event)");
TextBox1.Attributes.Add("onpaste", "return handleKeydown(event)");

Hope this will help you.

touseef4pk wrote:

Say i want to restrict to 3 three characters. It should not only to enter less than or more than three characters.

There are many ways:
1) Use Javascript - Write code onblur of the textbox to check if the length is equal to 3 or not.

<asp:TextBox ID="TextBox1" runat="server" onblur="javascript:validate();"></asp:TextBox>

function validate()
    {
        if(document.getElementById("TextBox1").value.length != 3)
        {
            alert("text lenghth must be three");
            document.getElementById("TextBox1").select();
            document.getElementById("TextBox1").focus();
            return false;
        }
        else
        {
            return true;
        }
    }

2) Use RegularExpressionValidator. You need to write a regular expression which checks the value entered is 3 characters.

[Edit]

touseef4pk wrote:

Please tell me how can i write reqular expression to limit characters upto three characters in textbox

Try this: \b[a-zA-Z]{3}\b

[/Edit]

touseef4pk wrote:

I want to allow only text in the textbox.

Text means alphanumeric which is the default for a textbox.
I guess you don't mean that. Please clarify.

Thanks for reply. Please tell me how can i write reqular expression to limit characters upto three characters in textbox. Actualy I mean to say that the input shoule be alphabetical only like "The". It should not accept numeric values. Please help me to resolve this conflict.

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