How PHP inserts a random keyword into a string to find an instance function

Insert several keywords randomly in an article (the number of keywords can be controlled)
Random numbers of random keywords are inserted at random positions in the article.
For example, the limit is to insert 3 keywords. Then the number of keywords inserted in the article is 3.
The inserted position is also a random position.

Seeking the example function to seek the master enlighten

Reply to discussion (solution)

If the article does not contain HTML tags, then the problem is relatively simple
But if it does, the problem is very complicated.

Are you going to take care of that? Think again!

is txt text, no HTML tags

$s =<<< txt inserts a random number of random keywords at random locations in an article by randomly inserting several keywords (the number of keywords you want to control) in an article. For example, the limit is to insert 3 keywords. Then the number of keywords inserted in the article is 3. The inserted position is also a random position. TXT, $w = ' keyword, random, insert ', echo foo ($s, $w), function foo ($txt, $word, $charset = ' gbk ') {foreach (Explode (', ', $word) as $v) $tmp  [] = Iconv ($charset, ' ucs-2 ', "" {$v} ");  $txt = Iconv ($charset, ' ucs-2 ', $txt); for ($i =0; $i
 
  Insert several keywords randomly in an article (the number of keywords can be controlled)
  
Random numbers of random keywords are inserted at random positions in the article.
  
Random
  
For example, the limit is to insert 3 words "Insert". Then in the text "keyword" You zhang Li Insert the number of keywords is 3.
  
The inserted position is also a random position.
  
 
  
 
  
  

  
   

  
 $s =<<< txt randomly inserts several keywords in an article (the number of keywords to be controllable) inserts random numbers of random keywords at random positions in the article. For example, the limit is to insert 3 keywords. Then the number of keywords inserted in the article is 3. The inserted position is also a random position. TXT, $w = ' keyword, random, insert ', echo foo ($s, $w), function foo ($txt, $word, $charset = ' gbk ') {foreach (Explode (', ', $word) as $v) $tmp  [] = Iconv ($charset, ' ucs-2 ', "" {$v} ");  $txt = Iconv ($charset, ' ucs-2 ', $txt); for ($i =0; $i 
    
      randomly inserts a number of keywords (the number of keywords can be controlled) 
     
 inserts random numbers of random keywords at random locations in the article. 
     
 Random 
     
 For example, the limit is to insert 3 keyword "Insert".   
  Then in the text "keyword" You zhang Li Insert the number of keywords is 3.   
  The 
     
 inserted position is also a random position. 
     
 
 If there is HTML code, what good method 
     
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