demo1.php

运行结果如下：
49993 squared is 2499300049
49994 squared is 2499400036
49995 squared is 2499500025
49996 squared is 2499600016
49997 squared is 2499700009
49998 squared is 2499800004
49999 squared is 2499900001
总共占用的内存大小为:1.28 mb
总共占用的时间为:5秒
demo2.php
$i*$i;
  }
}
foreach(squares(0,50000) as $n=>$square ){
  echo $n.' squared is '.$square.PHP_EOL;
}
$endTime = time();
$useTime = $endTime-$startTime;
$endMemory = memory_get_usage(); 
$useMemory = $endMemory-$startMemory;
echo "总共占用的内存大小为:".convert($useMemory).PHP_EOL;
echo "总共占用的时间为:".$useTime.'秒'.PHP_EOL;
运行demo2.php结果如下：
49988 squared is  2498800144
49989 squared is  2498900121
49990 squared is  2499000100
49991 squared is  2499100081
49992 squared is  2499200064
49993 squared is  2499300049
49994 squared is  2499400036
49995 squared is  2499500025
49996 squared is  2499600016
49997 squared is  2499700009
49998 squared is  2499800004
49999 squared is  2499900001
总共占用的内存大小为:32 b
总共占用的时间为:5秒