php去除html标识截取字符串

最近需要在HTML的内容中提取一段文本作为简介，如果用普通的办法提取那么将有可能出现截取了半个HTML标志的情况，会破坏页面布局， 为此添加了这么一个函数，可完美解决此问题！！注意在这里你截取的字符数是不含HTML标志的！！

1. <?php   
   
2. /**  
   4 s; O2 P5 I6 t' q& ^
3. * 截取HTML字符串 允许忽略HTML标志不计  
   7 F/ q( \3 ?: v+ q3 A
4. *  
   ; A) [4 U- t" s7 m. l6 d8 q/ \
5. * Author：学无止境  
   ( ]* ?0 R% J' T
6. * Email：xjtdy888@163.com  
   ! i% _4 x' L1 ]
7. * QQ: 339534039  
   
8. * Home:http://www.phpos.org  
   8 B+ H$ B" d; h
9. * Blog:http://hi.baidu.com/phps  
   # h5 N, I( Q3 r; H! `
10. *  
    
11. * 转载请保留作者信息  
    7 K  [1 g" e. i$ K7 F
12. 
    , u$ J& b& _4 x9 G  L
13. *   
    ( q. V) `/ c" W2 h
14. * @param 要截取的HTML $str  
    
15. * @param 截取的数量 $num  
    
16. * @param 是否需要加上更多 $more  
    
17. * @return 截取串  
    
18. */  
    
19. function phpos_chsubstr_ahtml($str,$num,$more=false)   
    3 r) g; w* t5 ~  O
20. {   
    : S( x; o' ^7 M7 ~% T  L, _
21.     $leng=strlen($str);   
    
22.       if($num>=$leng)      return $str;   
    ; h# Z4 |9 g$ K) j. u$ F
23.     $word=0;   
    
24.     $i=0;                        /** 字符串指针 **/  
    
25.     $stag=array(array());        /** 存放开始HTML的标志 **/  
    
26.     $etag=array(array());        /** 存放结束HTML的标志 **/  
    7 v  E4 s$ Z1 ~5 T0 w' P  I
27.     $sp = 0;   
    
28.     $ep = 0;   
    
29.       while($word!=$num)   
    1 |" b: n% {* x) p! D5 U% Z4 o0 n8 B
30.       {   
    
31.   
    1 t8 p0 W% s  F4 ~  e$ k9 {
32.           if(ord($str[$i])>128)   
    & W5 ~+ t3 K- G  ?8 m8 H
33.           {   
    
34.             //$re.=substr($str,$i,3);   
    
35.             $i+=3;   
    
36.             $word++;   
    
37.           }   
    2 Z/ V0 O' r- q5 W, ^. U. @4 H" _
38.           else if ($str[$i]=='<')   
    
39.           {   
    
40.               if ($str[$i+1] == '!')   
    
41.               {   
    
42.                 $i++;   
    + m9 p) R) E% D, W" ^6 R$ W
43.                   continue;   
    
44.               }   
    
45.   
    
46.               if ($str[$i+1]=='/')      
    
47.               {   
    
48.                 $ptag=$etag ;   
    * Y  g* b( F9 h6 N  [
49.                 $k=$ep;   
    ( }9 y0 W( B# n( g
50.                 $i+=2;   
    
51.               }   
    
52.               else                       
    
53.               {   
    % s  I! S8 s  d4 Y! u
54.                 $ptag=$stag;   
    0 a/ e$ i1 ~/ I9 t6 R
55.                 $i+=1;   
    
56.                 $k=$sp;   
    
57.               }   
    
58.   
    " f  G& D, C5 M* @+ t
59.               for(;$i<$leng;$i++)           
    ) g. r- s0 g& a- x3 s4 g
60.               {   
    
61.                   if ($str[$i] == ' ')   
    
62.                   {   
    " {! J7 ]' a3 u: [1 c/ `- P* w
63.                     $ptag[$k] = implode('',$ptag[$k]);   
    
64.                     $k++;   
    
65.                       break;   
      G9 V' d3 j8 I! p: w, R
66.                   }   
    
67.                   if ($str[$i] != '>')   
    # E$ ^5 i# l; q/ U1 H( i
68.                   {   
    
69.                     $ptag[$k][]=$str[$i];   
    
70.                       continue;   
    
71.                   }   
    
72.                   else                  
    ; B5 p2 q! M4 S* @  \1 C! I" @
73.                   {   
    8 y  `7 I  D( @* z% R4 k
74.                     $ptag[$k] = implode('',$ptag[$k]);   
    
75.                     $k++;   
    
76.                       break;   
    
77.                   }   
    
78.               }   
    
79.             $i++;   
    ) n. r$ h7 t" @5 L
80.               continue;   
    
81.           }   
    + E5 }; p% v& c% {' U: g
82.           else  
    
83.           {   
    
84.             //$re.=substr($str,$i,1);   
    
85.             $word++;   
    5 A' K& `- i+ v; c* L, Y0 F" k
86.             $i++;   
    
87.           }   
    
88.       }   
    
89.       foreach ($etag as $val)   
    
90.       {   
    
91.         $key1=array_search($val,$stag);   
    
92.           if ($key1 !== false)          unset($stag[$key]);   
    8 a, R( K# ?* y
93.       }   
    
94.       foreach ($stag as $key => $val)   
    2 {) J& e6 L9 i! f% B
95.       {   
    ; i6 o2 s! i" O
96.           if (in_array($val,array('br','img'))) unset($stag[$key1]);   
    
97.       }   
    
98.     array_reverse($stag);   
    
99.     $ends = '</'.implode('></',$stag).'>';   
    1 E2 {) ~: I) L2 P! `' o
100.     $re = substr($str,0,$i).$ends;   
     % F5 Z0 u4 G; @# K- m" U
101.       if($more)    $re.='...';   
     : W; y: R$ \$ g$ i% ?4 ^8 N
102.       return $re;   
     
103. }   
     4 u3 u  u  g9 x8 \7 a
104.   
     
105. $str=<<<EOF   
     + L( v: m+ L  N7 X/ t
106. <h3>What is the <acronym>GNU</acronym> pr<a><a><a>oject?</h3>   
     / A# S0 J% S, m1 }- O' N
107. <p>The <acronym>GNU</acronym> Project was launched in 1984 to develop a complete Unix-like operating system which is <a href="http://www.gnu.org/philosophy/free-sw.html">free software</a>: the <acronym>GNU</acronym> system. Variants of the <acronym>GNU</acronym> operating system, which use the kernel called Linux, are now widely used; though these systems are often referred to as “Linux”, they are more accurately called <a href="http://www.gnu.org/gnu/linux-and-gnu.html">GNU/Linux systems</a>. </p>   
     
108. <p><acronym>GNU</acronym> is a recursive acronym for “GNU's Not Unix”; it is pronounced <em>guh-noo</em>, approximately like <em>canoe</em>.</p>  
     , A4 p9 t) j3 j$ B5 K" J
109. <h3>What is Free Software?</h3>  
     0 [6 j# ~( B; X6 f: k' T
110. <p>“<a href="http://www.gnu.org/philosophy/free-sw.html">Free software</a>” is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech”, not as in “free beer”.</p>  
     ) \7 I- A. h" s+ c& ~1 B" U
111. <p>Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it refers to four kinds of freedom, for the users of the software:</p>   
     
112. <ul>   
     , w6 H# i6 y; d; b& @7 {
113.       <li>The freedom to run the program, for any purpose (freedom 0). </li>   
     8 a3 C9 I# M, v, Z; E% b! Y
114.       <li>The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this. </li>   
     7 Q) N4 C. \8 }- q
115.       <li>The freedom to redistribute copies so you can help your neighbor (freedom 2). </li>   
     
116.       <li>The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this. </li>   
     # v* o  |9 Q# d) w
117. </ul>   
     7 e+ P/ C  a- T+ Z; Z: C# \
118. <h3>What is the Free Software Foundation?</h3>   
     
119. <p>The <a href="http://www.fsf.org/">Free Software Foundation</a> (<abbr title="Free Software Foundation">) is the principal organizational sponsor of the Project. The receives very little funding from corporations or grant-making foundations, but relies on support from individuals like you. </abbr>) is the principal organizational sponsor of the Project. The receives very little funding from corporations or grant-making foundations, but relies on support from individuals like you. </p>   
     3 T# R/ F5 j1 f# l" J! O
120. <p>Please consider helping the <abbr>by , or by . If you use Free Software in your business, you can also consider or as a way to support the . </abbr>by , or by . If you use Free Software in your business, you can also consider or as a way to support the . </p>   
     
121. <p>The <acronym>GNU</acronym> project supports the mission of the <abbr>to preserve, protect and promote the freedom to use, study, copy, modify, and redistribute computer software, and to defend the rights of Free Software users. We support the on the Internet, , and the unimpeded by private monopolies. You can also learn more about these issues in the book . </abbr>to preserve, protect and promote the freedom to use, study, copy, modify, and redistribute computer software, and to defend the rights of Free Software users. We support the on the Internet, , and the unimpeded by private monopolies. You can also learn more about these issues in the book . </p>   
     ) [8 m5 z  S5 k. B
122. <!--   
     
123. Keep link lines at 72 characters or lynx will break them poorly   
     
124. Obviously, we list ONLY the most useful/important URLs here   
     9 b+ U" J. C( n5 O
125. Keep it short and sweet: 3 lines and 2 columns is already enough   
     0 q) T: n; s% f6 u% y
126. --><!-- BEGIN GNUmenu -->   
     
127. EOF;   
     9 U  f$ V" U1 V6 n  z9 b& |% k
128. echo phpos_chsubstr_ahtml($str,800);   
     
129. ?>   
     8 Z. b+ n$ m& e

Copy