一个验证用户名的正则表达式

求一个验证用户名的正则表达式
各位大哥大姐，晚辈求一个验证用户名的正则表达式，苦苦思索了一个星期还是没有弄出来，本人愚钝，还望大家指教！
VBscript编程要求用户名的字符控制在3至20个之间，由中文、大小写字母、数字、下划线、小数点、减号组成，必须以中英文或数字开头结尾且下划线、小数点、减号这三个字符中的其中一个的组合不能是连续的 a__a或a--a或a..a 这样的，但可以 a_a.a_a.a_a-a-a-a_a-a.a.a.a这样的。
如果超出这个范围则用户名不通过。
就是一直弄不明白下划线、小数点、减号这三个字符中的其中一个的组合的问题，头都大了
此为不符合的正则：
^.{0,2}$|.{21,}|^[^A-Za-z0-9\u4E00-\u9FA5]|[^\w\u4E00-\u9FA5.-]|([_.-])\1
input id=strs value="a_a.a_a.a_a-a-a_a-a" size=40input type=button onclick=regtest(strs.value) value="检查"</textarea...<a href="https://www.tulaoshi.com/n/20160219/1605427.html" target="_blank">[ 查看全文 ]</a></p> <div class="img_yyy_2"> <span>2016-02-19</span> <i>标签:</i> <div class="yyy_2_a"><a href="https://www.tulaoshi.com/webkaifa/" target="_blank">Web开发</a></div> </div> </div> </div> </div> <div class="xiangguan_gg xiangguan_reader clearfix"> <div class="xiang_892_1" style="width:1158px;"> <h3><a href="https://www.tulaoshi.com/n/20160219/1605427.html" target="_blank">一个验证用户名的正则表达式</a>的相关文章</h3> </div> <div class="xiang_892_2" style="width:1158px;"> <ul id="loadmore_container" style="width:1158px;"> <li> <div class="xiang_892_2_1"><a href="/reader/1605406" target="_blank"><img src="https://img.tulaoshi.com/201602/19/6057ba70a5df69e53f0aa1907a952218_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A 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target="_blank">正则表达式基础</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/webkaifa/" target="_blank">Web开发</a></div> <div class="span_em_123">前言正则表达式是烦琐的，但是强大的，学会之后的应用会让你除了提高效率外，会给你带来绝对的成就感。只要认真去阅读这些资料，加上应用的时候进行一定的参考，掌握正则表达式不是问题。索引 1. 引子目前，正则表达式已经在很多软件中得到广泛的应用，包括*nix（Linux, Unix等），HP等操作系统，PHP，C#，Java等开发环境，以及很多的应用软件中，都可以看到正则表达式的影子。正则...<a href="https://www.tulaoshi.com/n/20160219/1605226.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/今晩报/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/16.jpg" /><span>今晩报</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">3</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1592284" target="_blank"><img src="https://img.tulaoshi.com/201602/19/fac80cfa6fceebb9ae109e6134776932_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160219/1592284.html" target="_blank">常用正则表达式范例方便表单验证</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/webkaifa/" target="_blank">Web开发</a></div> <div class="span_em_123">代码如下：验证数字：^[0-9]*$ 验证n位的数字：^\d{n}$ 验证至少n位数字：^\d{n,}$ 验证m-n位的数字：^\d{m,n}$ 验证零和非零开头的数字：^(0|[1-9][0-9]*)$ 验证有两位小数的正实数：^[0-9]+(.[0-9]{2})?$ 验证有1-3位小数的正实数：^[0-9]+(.[0-9]{1,3})?$ 验证非零的正整数：^\+?[1-9][0-9]*$ 验证非零的负整数：^\-[1-9][0-9]*$ 验证非负整数（正整数 + 0） ^\d+$ 验证非正整数（负整数 + 0）...<a href="https://www.tulaoshi.com/n/20160219/1592284.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/一起看烟花99/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/4.jpg" /><span>一起看烟花99</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">15</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1509374" target="_blank"><img src="https://img.tulaoshi.com/201601/29/a850d1d89c860be16546614900e5cfd4_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160129/1509374.html" target="_blank">解析正则表达式（原创）</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/asp/" target="_blank">ASP</a></div> <div class="span_em_123"> 最近很多帖子问如何将内容从数据库取出后换行，这就要用到正则表达式。简单的说，正则表达式是一种可以用于模式匹配和替换的强有力的工具。我们可以在许多编程语言中找到正则表达式的身影，例如，vi编辑器，Perl或PHP脚本语言，以及awk或sed shell程序等。此外，象JavaScript这种客户端的脚本语言也提供了对正则表达式的支持。由此可见，正则表达式已经超出了某种...<a href="https://www.tulaoshi.com/n/20160129/1509374.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/倪金威sunny/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/14.jpg" /><span>倪金威sunny</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">2</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1508355" target="_blank"><img src="https://img.tulaoshi.com/201601/29/f5f025b3fd2121632e22d0d45b530bc6_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160129/1508355.html" target="_blank">正则表达式简介（14）</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/asp/" target="_blank">ASP</a></div> <div class="span_em_123"> 14.后向引用正则表达式一个最重要的特性就是将匹配成功的模式的某部分进行存储供以后使用这一能力。请回想一下，对一个正则表达式模式或部分模式两边添加圆括号将导致这部分表达式存储到一个临时缓冲区中。可以使用非捕获元字符 '?:', '?=', or '?!' 来忽略对这部分正则表达式的保存。所捕获的每个子匹配都按照在正则表达式模式中从左至右所遇到的内容存储。存储子匹配的缓冲区编号从 1 开始，...<a href="https://www.tulaoshi.com/n/20160129/1508355.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/沙漠的小草l/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/15.jpg" /><span>沙漠的小草l</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">5</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1489021" target="_blank"><img src="https://img.tulaoshi.com/201601/29/437fe290a97da0b9d554b72590f83804_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160129/1489021.html" target="_blank">正则表达式使用详解（一）</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/php/" target="_blank">PHP</a></div> <div class="span_em_123"> 如果我们问那些UNIX系统的爱好者他们最喜欢什么，答案除了稳定的系统和可以远程启动之外，十有八九的人会提到正则表达式；如果我们再问他们最头痛的是什么，可能除了复杂的进程控制和安装过程之外，还会是正则表达式。那么正则表达式到底是什么？如何才能真正的掌握正则表达式并正确的加以灵活运用？本文将就此展开介绍，希望能够对那些渴望了解和掌握正则表达式的读者有所助益。 ...<a href="https://www.tulaoshi.com/n/20160129/1489021.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/举步相思/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/1.jpg" /><span>举步相思</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">2</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1601583" target="_blank"><img src="https://img.tulaoshi.com/201602/19/f2c28873f3a0ca0c3e2f5d98bad5427e_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160219/1601583.html" target="_blank">正则表达式详述三</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/webkaifa/" target="_blank">Web开发</a></div> <div class="span_em_123">当表达式被检查的时候，文字符号提供了编辑正则表达式的方法。利用文字符号可以使到正则表达式保持为常数。例如，如果你在一个循环中使用文字符号来构造一个正则表达式，正则表达式不需进行反复编译。正则表达式对象构造器，例如，new RegExp("ab+c")，提供正则表达式的运行时编译。当你知道正则表达式的模式会变化的时候，应该使用构造函数，或者你不知道正则表达式的模式，而它们是从另外的源获得的时...<a href="https://www.tulaoshi.com/n/20160219/1601583.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/人YG/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/3.jpg" /><span>人YG</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">3</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1593298" target="_blank"><img src="https://img.tulaoshi.com/201602/19/3970cde788ec58a4a6153f2f3982c99b_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160219/1593298.html" target="_blank">JavaScript 正则表达式解析</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/webkaifa/" target="_blank">Web开发</a></div> <div class="span_em_123">JavaScript的RegExp对象和String对象定义了使用正则表达式来执行强大的模式匹配和文本检索与替换函数的方法. 在JavaScript中,正则表达式是由一个RegExp对象表示的.当然,可以使用一个RegExp()构造函数来创建RegExp对象,也可以用 JavaScript 1.2中的新添加的一个特殊语法来创建RegExp对象.就像字符串直接量被定义为包含在引号内的字符一样,正则表达式直接量也被定义为包含在一对斜杠 (/)之间的字符.所以,Ja...<a href="https://www.tulaoshi.com/n/20160219/1593298.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/lowesdts458171/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/28.jpg" /><span>lowesdts458171</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">3</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> <li> <div class="xiang_892_2_1"><a href="/reader/1508394" target="_blank"><img src="https://img.tulaoshi.com/201601/29/66cb819a81ea7202325ddad16df05150_thumb_189.jpg" width="224" height="173"></a></div> <div class="xiang_right clearfix"> <div class="xiang_right_1"><A href="https://www.tulaoshi.com/n/20160129/1508394.html" target="_blank">正则表达式简介（11）</A></div> <div class="xiang_righ_lable">标签：<a href="https://www.tulaoshi.com/asp/" target="_blank">ASP</a></div> <div class="span_em_123"> 11.限定符有时候不知道要匹配多少字符。为了能适应这种不确定性，正则表达式支持限定符的概念。这些限定符可以指定正则表达式的一个给定组件必须要出现多少次才能满足匹配。下表给出了各种限定符及其含义的说明：字符 &n...<a href="https://www.tulaoshi.com/n/20160129/1508394.html" target="_blank">[ 查看全文 ]</a></div> <div class="span_em "> <div class="cai_list_font"><a href="/user/烤肉G眼绿/" target="_blank"><img src="https://static.tulaoshi.com/html/tulaoshi_new/images/touxiang/24.jpg" /><span>烤肉G眼绿</span></a></div> <span class="font_span"><a class="em_s" href="javascript:;">0</a><a class="em_s2" href="javascript:;">1</a></span></div> </div> </li> </ul> <div id="pages" class="clearfix"> <a href="/reader/21817.html">上一页</a><a href="/reader/21814.html">21814</a><a href="/reader/21815.html">21815</a><a href="/reader/21816.html">21816</a><a href="/reader/21817.html">21817</a><a 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