HTML字符实体(Character Entities),转义字符串(Escape Sequence)

为什么要用转义字符串?

HTML中<,>,&等有特殊含义(<,>,用于链接签,&用于转义),不能直接使用。这些符号是不显示在我们最终看到的网页里的,那如果我们希望在网页中显示这些符号,该怎么办呢?

这就要说到HTML转义字符串(Escape Sequence)了。

转义字符串(Escape Sequence)也称字符实体(Character Entity)。在HTML中,定义转义字符串的原因有两个:第一个原因是像“<”和“>”这类符号已经用来表示HTML标签,因此就不能直接当作文本中的符号来使用。为了在HTML文档中使用这些符号,就需要定义它的转义字符串。当解释程序遇到这类字符串时就把它解释为真实的字符。在输入转义字符串时,要严格遵守字母大小写的规则。第二个原因是,有些字符在ASCII字符集中没有定义,因此需要使用转义字符串来表示。

转义字符串的组成

转义字符串(Escape Sequence),即字符实体(Character Entity)分成三部分:第一部分是一个&符号,英文叫ampersand;第二部分是实体(Entity)名字或者是#加上实体(Entity)编号;第三部分是一个分号。

比如,要显示小于号(<),就可以写 &lt; 或者 &#60; 。

用实体(Entity)名字的好处是比较好理解,一看lt,大概就猜出是less than的意思,但是其劣势在于并不是所有的浏览器都支持最新的Entity名字。而实体(Entity)编号,各种浏览器都能处理。

提示:实体名称(Entity)是区分大小写的。

备注:同一个符号,可以用“实体名称”和“实体编号”两种方式引用,“实体名称”的优势在于便于记忆,但不能保证所有的浏览器都能顺利识别它,而“实体编号”则没有这种担忧,但它实在不方便记忆。

如何显示空格?

通常情况下,HTML会自动截去多余的空格。不管你加多少空格,都被看做一个空格。比如你在两个字之间加了10个空格,HTML会截去9个空格,只保留一个。为了在网页中增加空格,你可以使用&nbsp;表示空格。


HTML特殊转义字符列表

最常用的字符实体
Character Entities

显示 说明 实体名称 实体编号
半方大的空白 &ensp; &#8194;
全方大的空白 &emsp; &#8195;
不断行的空白格 &nbsp; &#160;
< 小于 &lt; &#60;
> 大于 &gt; &#62;
& &符号 &amp; &#38;
" 双引号 &quot; &#34;
© 版权 &copy; &#169;
® 已注册商标 &reg; &#174;
商标(美国) &#8482;
× 乘号 &times; &#215;
÷ 除号 &divide; &#247;

ISO 8859-1 (Latin-1)字符集

HTML 4.01 支持 ISO 8859-1 (Latin-1) 字符集。

备注:为了方便起见,以下表格中,“实体名称”简称为“名称”,“实体编号”简称为“编号”

显示 名称 编号 显示 名称 编号 显示 名称 编号 显示 名称 编号 显示 名称 编号
  &nbsp; &#160; ¡ &iexcl; &#161; ¢ &cent; &#162; £ &pound; &#163; ¤ &curren; &#164;
¥ &yen; &#165; ¦ &brvbar; &#166; § &sect; &#167; ¨ &uml; &#168; © &copy; &#169;
ª &ordf; &#170; « &laquo; &#171; ¬ &not; &#172; ­ &shy; &#173; ® &reg; &#174;
¯ &macr; &#175; ° &deg; &#176; ± &plusmn; &#177; ² &sup2; &#178; ³ &sup3; &#179;
´ &acute; &#180; µ &micro; &#181; &para; &#182; · &middot; &#183; ¸ &cedil; &#184;
¹ &sup1; &#185; º &ordm; &#186; » &raquo; &#187; ¼ &frac14; &#188; ½ &frac12; &#189;
¾ &frac34; &#190; ¿ &iquest; &#191; À &Agrave; &#192; Á &Aacute; &#193; Â &Acirc; &#194;
à &Atilde; &#195; Ä &Auml; &#196; Å &Aring; &#197; Æ &AElig; &#198; Ç &Ccedil; &#199;
È &Egrave; &#200; É &Eacute; &#201; Ê &Ecirc; &#202; Ë &Euml; &#203; Ì &Igrave; &#204;
Í &Iacute; &#205; Î &Icirc; &#206; Ï &Iuml; &#207; Ð &ETH; &#208; Ñ &Ntilde; &#209;
Ò &Ograve; &#210; Ó &Oacute; &#211; Ô &Ocirc; &#212; Õ &Otilde; &#213; Ö &Ouml; &#214;
× &times; &#215; Ø &Oslash; &#216; Ù &Ugrave; &#217; Ú &Uacute; &#218; Û &Ucirc; &#219;
Ü &Uuml; &#220; Ý &Yacute; &#221; Þ &THORN; &#222; ß &szlig; &#223; à &agrave; &#224;
á &aacute; &#225; â &acirc; &#226; ã &atilde; &#227; ä &auml; &#228; å &aring; &#229;
æ &aelig; &#230; ç &ccedil; &#231; è &egrave; &#232; é &eacute; &#233; ê &ecirc; &#234;
ë &euml; &#235; ì &igrave; &#236; í &iacute; &#237; î &icirc; &#238; ï &iuml; &#239;
ð &eth; &#240; ñ &ntilde; &#241; ò &ograve; &#242; ó &oacute; &#243; ô &ocirc; &#244;
õ &otilde; &#245; ö &ouml; &#246; ÷ &divide; &#247; ø &oslash; &#248; ù &ugrave; &#249;
ú &uacute; &#250; û &ucirc; &#251; ü &uuml; &#252; ý &yacute; &#253; þ &thorn; &#254;
ÿ &yuml; &#255;

数学和希腊字母标志
symbols, mathematical symbols, and Greek letters

显示 名称 编号 显示 名称 编号 显示 名称 编号 显示 名称 编号 显示 名称 编号
ƒ &fnof; &#402; Α &Alpha; &#913; Β &Beta; &#914; Γ &Gamma; &#915; Δ &Delta; &#916;
Ε &Epsilon; &#917; Ζ &Zeta; &#918; Η &Eta; &#919; Θ &Theta; &#920; Ι &Iota; &#921;
Κ &Kappa; &#922; Λ &Lambda; &#923; Μ &Mu; &#924; Ν &Nu; &#925; Ξ &Xi; &#926;
Ο &Omicron; &#927; Π &Pi; &#928; Ρ &Rho; &#929; Σ &Sigma; &#931; Τ &Tau; &#932;
Υ &Upsilon; &#933; Φ &Phi; &#934; Χ &Chi; &#935; Ψ &Psi; &#936; Ω &Omega; &#937;
α &alpha; &#945; β &beta; &#946; γ &gamma; &#947; δ &delta; &#948; ε &epsilon; &#949;
ζ &zeta; &#950; η &eta; &#951; θ &theta; &#952; ι &iota; &#953; κ &kappa; &#954;
λ &lambda; &#955; μ &mu; &#956; ν &nu; &#957; ξ &xi; &#958; ο &omicron; &#959;
π &pi; &#960; ρ &rho; &#961; ς &sigmaf; &#962; σ &sigma; &#963; τ &tau; &#964;
υ &upsilon; &#965; φ &phi; &#966; χ &chi; &#967; ψ &psi; &#968; ω &omega; &#969;
? &thetasym; &#977; ? &upsih; &#978; ? &piv; &#982; &bull; &#8226; &hellip; &#8230;
&prime; &#8242; &Prime; &#8243; &oline; &#8254; &frasl; &#8260; &weierp; &#8472;
&image; &#8465; &real; &#8476; &trade; &#8482; &alefsym; &#8501; &larr; &#8592;
&uarr; &#8593; &rarr; &#8594; &darr; &#8595; &harr; &#8596; &crarr; &#8629;
&lArr; &#8656; &uArr; &#8657; &rArr; &#8658; &dArr; &#8659; &hArr; &#8660;
&forall; &#8704; &part; &#8706; &exist; &#8707; &empty; &#8709; &nabla; &#8711;
&isin; &#8712; &notin; &#8713; &ni; &#8715; &prod; &#8719; &sum; &#8721;
&minus; &#8722; &lowast; &#8727; &radic; &#8730; &prop; &#8733; &infin; &#8734;
&ang; &#8736; &and; &#8743; &or; &#8744; &cap; &#8745; &cup; &#8746;
&int; &#8747; &there4; &#8756; &sim; &#8764; &cong; &#8773; &asymp; &#8776;
&ne; &#8800; &equiv; &#8801; &le; &#8804; &ge; &#8805; &sub; &#8834;
&sup; &#8835; &nsub; &#8836; &sube; &#8838; &supe; &#8839; &oplus; &#8853;
&otimes; &#8855; &perp; &#8869; &sdot; &#8901; ? &lceil; &#8968; ? &rceil; &#8969;
? &lfloor; &#8970; ? &rfloor; &#8971; ? &lang; &#9001; ? &rang; &#9002; &loz; &#9674;
&spades; &#9824; &clubs; &#9827; &hearts; &#9829; &diams; &#9830;

重要的国际标记
markup-significant and internationalization characters

显示 名称 编号 显示 名称 编号 显示 名称 编号 显示 名称 编号 显示 名称 编号
" &quot; &#34; & &amp; &#38; < &lt; &#60; > &gt; &#62; Π&OElig; &#338;
œ &oelig; &#339; Š &Scaron; &#352; š &scaron; &#353; Ÿ &Yuml; &#376; ˆ &circ; &#710;
˜ &tilde; &#732; &ensp; &#8194; &emsp; &#8195; &thinsp; &#8201; &zwnj; &#8204;
&zwj; &#8205; &lrm; &#8206; &rlm; &#8207; &ndash; &#8211; &mdash; &#8212;
&lsquo; &#8216; &rsquo; &#8217; &sbquo; &#8218; &ldquo; &#8220; &rdquo; &#8221;
&bdquo; &#8222; &dagger; &#8224; &Dagger; &#8225; &permil; &#8240; &lsaquo; &#8249;
&rsaquo; &#8250; &euro; &#8364;

JavaScript转义符

转义序列 字符
\b 退格
\f 走纸换页
\n 换行
\r 回车
\t 横向跳格 (Ctrl-I)
\' 单引号
\" 双引号
\\ 反斜杠

编程的时候要注意特殊字符的问题,很多运行时出现的问题都是因为特殊字符的出现而引起的。

注意,由于反斜杠本身用作转义符,因此不能直接在脚本中键入一个反斜杠。如果要产生一个反斜杠,必须一起键入两个反斜杠 (\\)。


编码转换(to Unicode)

(程序代码来源于网络)

Js版

<script>
     test = "你好abc"
     str = ""
     for( i=0;    i<test.length; i++ )
     {
      temp = test.charCodeAt(i).toString(16);
      str    += "\\u"+ new Array(5-String(temp).length).join("0") +temp;
     }
     document.write (str)
</script>


vbs版


Function Unicode(str1)
     Dim str,temp
     str = ""
     For i=1    to len(str1)
      temp = Hex(AscW(Mid(str1,i,1)))
      If len(temp) < 5 Then    temp = right("0000" & temp, 4)
      str = str & "\u" & temp
     Next
     Unicode = str
End Function


Function htmlentities(str)
     For i = 1 to Len(str)
         char = mid(str, i, 1)
         If Ascw(char) > 128 then
             htmlentities = htmlentities & "&#" & Ascw(char) & ";"
         Else
             htmlentities = htmlentities & char
         End if
     Next
End Function

coldfusion

function nochaoscode(str)
{
     var new_str = “”;
     for(i=1; i lte len(str);i=i+1){
         if(asc(mid(str,i,1)) lt 128){
             new_str = new_str & mid(str,i,1);
         }else{
             new_str = new_str & “&##” & asc(mid(str,i,1));
         }
     }
     return new_str;
}


附:

在php中我们可以用mbstring的mb_convert_encoding函数实现这个正向及反向的转化。 如:


mb_convert_encoding ("你好", "HTML-ENTITIES", "gb2312"); //输出:&#20320;&#22909;

mb_convert_encoding ("&#20320;&#22909;", "gb2312", "HTML-ENTITIES"); //输出:你好

如果需要对整个页面转化,则只需要在php文件的头部加上这三行代码:

mb_internal_encoding("gb2312"); // 这里的gb2312是你网站原来的编码

mb_http_output("HTML-ENTITIES");

ob_start('mb_output_handler');

来源:HTML转义字符: http://114.xixik.com/character/

相关:正则表达式: http://114.xixik.com/regex/