How to implement keyword replacement in php

php method to implement keyword replacement: first use the strpos() function to find the location of the keyword, such as [strpos($content,$search)]; then use the substr_replace() function to replace the keyword .

substr_replace() function replaces part of a string with another string and returns the replaced string. If string is an array, the array is returned.

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Syntax:

substr_replace(string,replacement,start,length)

If the start parameter is a negative number and length is less than or equal to start, then length is 0.

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Code implementation:

//首先找到关键字所在位置，然后使用 substr_replace（系统函数）进行替换操作 
function str_replace_once($search,$replace,$content){ 
  //把图片描述去掉 
  $content=preg_replace("/alt=([^ >]+)/is",'',$content); 
  $pos=strpos($content,$search); 
  if($pos===false){ 
    return $haystack; 
  } 
  return substr_replace($content,$replace,$pos,strlen($search)); 
}

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