Detailed explanation of efficiency comparison examples of three types of string connections in PHP

There are roughly three types of String connections in php:

1. Use . to connect directly.

2. Use .= to connect.

3. First push into the array, and then connect through the join function.

The efficiency of these three methods are tested below:

The code of the first method is as follows:

<?php   
   function get_tm() {
   list ( $usec, $sec ) = explode ( " ", microtime () );
   return (( float ) $usec + ( float ) $sec);
   }
   
   $temp="test";
   $result="";
   define("num",100000);
   $start=get_tm();
  
   for($i=0;$i<num;$i++)
   {
     $result=$result.$temp;
   }
   echo get_tm()-$start;
   
?>

Run 4 times, excluding the first running time, three times The times are:

22.165272951126
22.003527164459
22.15947508812

The second method code is as follows:

<?php     
   function get_tm() {
   list ( $usec, $sec ) = explode ( " ", microtime () );
   return (( float ) $usec + ( float ) $sec);
   }
   
   $temp="test";
   $result="";
   define("num",100000);
   $start=get_tm();
  
   for($i=0;$i<num;$i++)
   {
     $result.=$temp;
   }
   echo get_tm()-$start;
   
?>

Run 4 times, excluding the first running time, The three times are:

3.1967310905457
3.1296961307526
3.0872850418091

The third method code is as follows:

<?php      
   function get_tm() {
   list ( $usec, $sec ) = explode ( " ", microtime () );
   return (( float ) $usec + ( float ) $sec);
   }
   
   $temp="test";
   $result="";
   $arr=array();
   define("num",100000);
   $start=get_tm();
  
   for($i=0;$i<num;$i++)
   {
     array_push($arr, $temp);
   }
   $result=join($arr);
   echo get_tm()-$start;
   
?>

Run 4 times, excluding the first running time , the three times are:

3.3184430599213
3.2759411334991
3.2663381099701

As can be seen from the above, string connection directly through . is the most inefficient.

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