blocks|key|1512819|text|今天我有一些空闲时间，从头开始写了一个解码器：entities.c，entities.h。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1512820|唯一具有外部链接的函数是|1512821|size_t+decode_html_entities_utf8(char+*dest,+const+char+*src);|code-block|syntax|javascript|1512822|如果src是空指针，字符串将从dest中获取，即实体将被就地解码。否则，解码后的字符串将被放入dest中--它应该指向一个足以容纳strlen(src)+%2B+1字符的缓冲区--而src将保持不变。|style|CODE|1512823|该函数将返回已解码字符串的长度。|1512824|请注意，我没有做过任何广泛的测试，所以很有可能会出现bug……|1512825|entityMap|0|LINK|mutability|MUTABLE|url|https://bitbucket.org/cggaertner/cstuff/src/master/entities.c|1|https://bitbucket.org/cggaertner/cstuff/src/master/entities.h^0|N|A|0|Y|A|1|0|0|0|2|3|F|4|1B|4|1T|F|2H|3|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@$A|13|B|14|1|15]|$A|16|B|17|1|18]]|C|$]]|$1|D|3|E|5|6|7|19|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|1A|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|1B|8|@$A|1C|B|1D|M|N]|$A|1E|B|1F|M|N]|$A|1G|B|1H|M|N]|$A|1I|B|1J|M|N]|$A|1K|B|1L|M|N]]|9|@]|C|$]]|$1|O|3|P|5|6|7|1M|8|@]|9|@]|C|$]]|$1|Q|3|R|5|6|7|1N|8|@]|9|@]|C|$]]|$1|S|3|-4|5|6|7|1O|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|Z]]|10|$5|V|W|X|C|$Y|11]]]]

I had some free time today and wrote a decoder from scratch: <a href="https://bitbucket.org/cggaertner/cstuff/src/master/entities.c" rel="noreferrer">entities.c</a>, <a href="https://bitbucket.org/cggaertner/cstuff/src/master/entities.h" rel="noreferrer">entities.h</a>.

The only function with external linkage is

<pre><code>size_t decode_html_entities_utf8(char *dest, const char *src);
</code></pre>

If <code>src</code> is a null pointer, the string will be taken from <code>dest</code>, ie the entities will be decoded in-place. Otherwise, the decoded string will be put in <code>dest</code> - which should point to a buffer big enough to hold <code>strlen(src) + 1</code> characters - and <code>src</code> will be unchanged.

The function will return the length of the decoded string.

Please note that I haven't done any extensive testing, so there's a high probability of bugs...

blocks|key|1512855|text|我编写了自己的无法转义的代码；非常简单，但完成了工作：pn_util.c|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1512856|entityMap|0|LINK|mutability|MUTABLE|url|http://github.com/felipec/msn-pecan/blob/master/pn_util.c#L870^0|R|9|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I wrote my own unescape code; very simplified, but does the job: <a href="http://github.com/felipec/msn-pecan/blob/master/pn_util.c#L870" rel="nofollow noreferrer">pn_util.c</a>

blocks|key|1512906|text|对于C中解码这些HTML实体的另一个开源参考，您可以查看命令行实用程序uni2ascii/ascii2uni。相关文件是用于实体查找的enttbl.{c，h}和从UTF32向下转换为UTF8的putu8.c。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1512907|uni2ascii|offset|length|1512908|entityMap|0|LINK|mutability|MUTABLE|url|http://billposer.org/Software/uni2ascii.html^0|0|0|9|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

For another open source reference in C to decoding these HTML entities you can check out the command line utility uni2ascii/ascii2uni. The relevant files are enttbl.{c,h} for entity lookup and putu8.c which down converts from UTF32 to UTF8.

<a href="http://billposer.org/Software/uni2ascii.html" rel="nofollow">uni2ascii</a>

blocks|key|1298217|text|功能描述:将特殊的HTML实体转换回字符。需要做一些修改，以满足您的要求。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1298218|char*+HtmlSpecialChars_Decode(char*+encodedHtmlSpecialEntities)
{
int+encodedLen+=+0;
int+escapeArrayLen+=+0;
static+char+decodedHtmlSpecialChars[TITLE_SIZE];
char+innerHtmlSpecialEntities[MAX_CONFIG_ITEM_SIZE];

/*+This+mapping+table+can+be+extended+if+necessary.+*/
static+const+struct+{
++++const+char*+encodedEntity;
++++const+char+decodedChar;
}+entityToChars[]+=+{
++++++++{"&lt;",+'<'},
++++++++{"&gt;",+'>'},
++++++++{"&amp;",+'&'},
++++++++{"&quot;",+'"'},
++++++++{"&#039;",+'\''},
++++};

if(strchr(encodedHtmlSpecialEntities,+'&')+==+NULL)
++++return+encodedHtmlSpecialEntities;

memset(decodedHtmlSpecialChars,+'\0',+TITLE_SIZE);
memset(innerHtmlSpecialEntities,+'\0',+MAX_CONFIG_ITEM_SIZE);
escapeArrayLen+=+sizeof(entityToChars)+/+sizeof(entityToChars[0]);


strcpy(innerHtmlSpecialEntities,+encodedHtmlSpecialEntities);
encodedLen+=+strlen(innerHtmlSpecialEntities);

for(int+i+=+0;+i+<+encodedLen;+i%2B%2B)
{
++++if(innerHtmlSpecialEntities[i]+==+'&')
++++{
++++++++/*+Potential+encode+char.+*/
++++++++char+*+tempEntities+=+innerHtmlSpecialEntities+%2B+i;

++++++++for(int+j+=+0;+j+<+escapeArrayLen;+j%2B%2B)
++++++++{
++++++++++++if(strncmp(tempEntities,+entityToChars[j].encodedEntity,+strlen(entityToChars[j].encodedEntity))+==+0)
++++++++++++{
++++++++++++++++int+index+=+0;
++++++++++++++++strncat(decodedHtmlSpecialChars,+innerHtmlSpecialEntities,+i);

++++++++++++++++index+=+strlen(decodedHtmlSpecialChars);
++++++++++++++++decodedHtmlSpecialChars[index]+=+entityToChars[j].decodedChar;
++++++++++++++++if(strlen(tempEntities)+>+strlen(entityToChars[j].encodedEntity))
++++++++++++++++{
++++++++++++++++++++/*+Not+to+the+end,+continue+*/
++++++++++++++++++++char+temp[MAX_CONFIG_ITEM_SIZE]+=+{'\0'};
++++++++++++++++++++strcpy(temp,+tempEntities+%2B+strlen(entityToChars[j].encodedEntity));
++++++++++++++++++++memset(innerHtmlSpecialEntities,+'\0',+MAX_CONFIG_ITEM_SIZE);
++++++++++++++++++++strcpy(innerHtmlSpecialEntities,+temp);

++++++++++++++++++++encodedLen+=+strlen(innerHtmlSpecialEntities);
++++++++++++++++++++i+=+-1;
++++++++++++++++}
++++++++++++++++else
++++++++++++++++++++encodedLen+=+0;

++++++++++++++++break;
++++++++++++}
++++++++}
++++}
}

if(encodedLen+!=+0)
++++strcat(decodedHtmlSpecialChars,+innerHtmlSpecialEntities);

return+decodedHtmlSpecialChars;|code-block|syntax|javascript|1298219|}|1298220|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Function Description: Convert special HTML entities back to characters.
Need to do some modifications to fit your requirement.

<pre><code>char* HtmlSpecialChars_Decode(char* encodedHtmlSpecialEntities)
{
int encodedLen = 0;
int escapeArrayLen = 0;
static char decodedHtmlSpecialChars[TITLE_SIZE];
char innerHtmlSpecialEntities[MAX_CONFIG_ITEM_SIZE];

/* This mapping table can be extended if necessary. */
static const struct {
 const char* encodedEntity;
 const char decodedChar;
} entityToChars[] = {
 {"&amp;lt;", '&lt;'},
 {"&amp;gt;", '&gt;'},
 {"&amp;amp;", '&amp;'},
 {"&amp;quot;", '"'},
 {"&amp;#039;", '\''},
 };

if(strchr(encodedHtmlSpecialEntities, '&amp;') == NULL)
 return encodedHtmlSpecialEntities;

memset(decodedHtmlSpecialChars, '\0', TITLE_SIZE);
memset(innerHtmlSpecialEntities, '\0', MAX_CONFIG_ITEM_SIZE);
escapeArrayLen = sizeof(entityToChars) / sizeof(entityToChars[0]);


strcpy(innerHtmlSpecialEntities, encodedHtmlSpecialEntities);
encodedLen = strlen(innerHtmlSpecialEntities);

for(int i = 0; i &lt; encodedLen; i++)
{
 if(innerHtmlSpecialEntities[i] == '&amp;')
 {
 /* Potential encode char. */
 char * tempEntities = innerHtmlSpecialEntities + i;

 for(int j = 0; j &lt; escapeArrayLen; j++)
 {
 if(strncmp(tempEntities, entityToChars[j].encodedEntity, strlen(entityToChars[j].encodedEntity)) == 0)
 {
 int index = 0;
 strncat(decodedHtmlSpecialChars, innerHtmlSpecialEntities, i);

 index = strlen(decodedHtmlSpecialChars);
 decodedHtmlSpecialChars[index] = entityToChars[j].decodedChar;
 if(strlen(tempEntities) &gt; strlen(entityToChars[j].encodedEntity))
 {
 /* Not to the end, continue */
 char temp[MAX_CONFIG_ITEM_SIZE] = {'\0'};
 strcpy(temp, tempEntities + strlen(entityToChars[j].encodedEntity));
 memset(innerHtmlSpecialEntities, '\0', MAX_CONFIG_ITEM_SIZE);
 strcpy(innerHtmlSpecialEntities, temp);

 encodedLen = strlen(innerHtmlSpecialEntities);
 i = -1;
 }
 else
 encodedLen = 0;

 break;
 }
 }
 }
}

if(encodedLen != 0)
 strcat(decodedHtmlSpecialChars, innerHtmlSpecialEntities);

return decodedHtmlSpecialChars;
</code></pre>

}

blocks|key|1298226|text|QString+UNESC(const+QString+&txt)+{
++++QStringList+bld;
++++static+QChar+AMP+=+'&',+SCL+=+';';
++++static+QMap<QString,+QString>+dec+=+{
++++++++{"&lt;",+"<"},+{"&gt;",+">"}
++++++,+{"&amp;",+"&"},+{"&quot;",+R"(")"},+{"&#039;",+"'"}+};

++++if(!txt.contains(AMP))+{+return+txt;+}

++++int+bgn+=+0,+pos+=+0;
++++while((pos+=+txt.indexOf(AMP,+pos))+!=+-1)+{
++++++++int+end+=+txt.indexOf(SCL,+pos)%2B1;
++++++++QString+val+=+dec[txt.mid(pos,+end+-+pos)];

++++++++bld+<<+txt.mid(bgn,+pos+-+bgn);

++++++++if(val.isEmpty())+{
++++++++++++end+=+txt.indexOf(AMP,+pos%2B1);
++++++++++++bld+<<+txt.mid(pos,+end+-+pos);
++++++++}+else+{
++++++++++++bld+<<+val;
++++++++}//+else+//+if(val.isEmpty())

++++++++bgn+=+end;+pos+=+end;
++++}//+while((pos+=+txt.indexOf(AMP,+pos))+!=+-1)

++++return+bld.join(QString());
}//+UNESC|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1298227|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>QString UNESC(const QString &amp;txt) {
 QStringList bld;
 static QChar AMP = '&amp;', SCL = ';';
 static QMap&lt;QString, QString&gt; dec = {
 {"&amp;lt;", "&lt;"}, {"&amp;gt;", "&gt;"}
 , {"&amp;amp;", "&amp;"}, {"&amp;quot;", R"(")"}, {"&amp;#039;", "'"} };

 if(!txt.contains(AMP)) { return txt; }

 int bgn = 0, pos = 0;
 while((pos = txt.indexOf(AMP, pos)) != -1) {
 int end = txt.indexOf(SCL, pos)+1;
 QString val = dec[txt.mid(pos, end - pos)];

 bld &lt;&lt; txt.mid(bgn, pos - bgn);

 if(val.isEmpty()) {
 end = txt.indexOf(AMP, pos+1);
 bld &lt;&lt; txt.mid(pos, end - pos);
 } else {
 bld &lt;&lt; val;
 }// else // if(val.isEmpty())

 bgn = end; pos = end;
 }// while((pos = txt.indexOf(AMP, pos)) != -1)

 return bld.join(QString());
}// UNESC
</code></pre>

I'm interested in unescaping text for example: <code>&amp;#x5c;</code> maps to <code>\</code> in C. Does anyone know of a good library?

As reference the Wikipedia <a href="http://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references" rel="noreferrer">List of XML and HTML Character Entity References</a>.

How to decode HTML Entities in C?

我对不转义的文本感兴趣，例如：&#x5c;映射到C中的\。有谁知道好的库吗？参考维基百科的。

问如何在C中解码HTML实体？
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