遍历数组的三种方式：foreach循环 | while + list + each组合循环 | for循环

  1. php

  2. //循环数组方法

  3. $arr = array();

  4. for( $i=0;$i<50000;$i++ ){

  5.    $arr[] = $i*rand(1000,9999);//随机整数

  6. }

  8. function getRunTime(){

  9.    list( $usec,$sec ) = explode(" ",microtime());

  10.    return ( (float)$usec+(float)$sec );

  11. }

  12. echo '#############first method for#################';

  13. $time_statr = getRunTime();

  14. $numc = count( $arr );

  15. for( $i=0;$i<$numc;$i++ ){

  16.    $str = $arr[$i];

  17. }

  18. $time_end = getRunTime();

  19. $time_used = $time_end-$time_statr;

  20. echo 'Used time of for:'.round($time_used, 7).'(s)

    '    ;

  21. unset( $str,$time_statr,$time_end,$time_used );

  22. echo '#############second method (while list each)#################';

  23. $time_statr = getRunTime();

  24. while( list( $key,$value ) = each( $arr ) ){

  25.    $str = $value;

  26. }

  27. $time_end = getRunTime();

  28. $time_used = $time_end-$time_statr;

  29. echo 'Used time of while:'.round($time_used, 7).'(s)

    '    ;

  30. unset($str, $key, $val, $time_start, $time_end, $time_used);

  31. echo '#############third method foreach#################';

  32. $time_statr = getRunTime();

  33. foreach( $arr as $key=>$value ){

  34.    $str = $value;

  35. }

  36. $time_end = getRunTime();

  37. $time_used = $time_end-$time_start;

  38. echo 'Used time of foreach:'.round($time_used, 7).'(s)

    '    ;

  40. ######################################Used time of for:0.003757(s)

  42. ######################################Used time of while:0.0147378(s)

  44. ######################################Used time of foreach:0.001509(s)