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( $i=0;$i50000;$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)