how to change array keys from uppercase to lowercase?

问题

I have an array with keys uppercase and i want to change them to lowercase. How can I do that. I tried to do

//$data1 = array();
foreach ($row as $key => $value)
{
    $key = strtolower($str);
    $data1[$key] = $value;
}
$data[] = $data1;

But it is not working

This is my array, it also contains objects, it is a fetch from a database, sry for printing it all

Array ( [0] => stdClass Object ( [ID] => 4 [TUTOR_ID] => 4 [PRICE] => 25 [TITLE] => Introduction Mathematical Analysis [FEATURED] => 1 [DESCRIPTION] => This course provides the user with a smooth introduction in the field of Mathematical Analysis. [DATE_ADDED] => 0 [rating] => 2 [subscribers] => 18 [categories] => Array ( ) [languages] => Array ( ) [chapters] => Array ( [0] => stdClass Object ( [ID] => 49 [COURSE_ID] => 4 [START_TIME] => 3977118 [END_TIME] => 3982720 [DURATION] => 3600 [TITLE] => Conclusions & Questioning [DESCRIPTION] => Wrap-up and Discussions. ) [1] => stdClass Object ( [ID] => 48 [COURSE_ID] => 4 [START_TIME] => 3821895 [END_TIME] => 3826718 [DURATION] => 4200 [TITLE] => Chapter 23 [DESCRIPTION] => Chapter 23\'s Description ) [2] => stdClass Object ( [ID] => 47 [COURSE_ID] => 4 [START_TIME] => 3653545 [END_TIME] => 3658238 [DURATION] => 4200 [TITLE] => Chapter 22 [DESCRIPTION] => Chapter 22\'s Description ) [3] => stdClass Object ( [ID] => 46 [COURSE_ID] => 4 [START_TIME] => 3490243 [END_TIME] => 3495917 [DURATION] => 4200 [TITLE] => Chapter 21 [DESCRIPTION] => Chapter 21\'s Description ) [4] => stdClass Object ( [ID] => 45 [COURSE_ID] => 4 [START_TIME] => 3338210 [END_TIME] => 3343938 [DURATION] => 4200 [TITLE] => Chapter 20 [DESCRIPTION] => Chapter 20\'s Description ) [5] => stdClass Object ( [ID] => 44 [COURSE_ID] => 4 [START_TIME] => 3169837 [END_TIME] => 3174154 [DURATION] => 4200 [TITLE] => Chapter 19 [DESCRIPTION] => Chapter 19\'s Description ) [6] => stdClass Object ( [ID] => 43 [COURSE_ID] => 4 [START_TIME] => 3016815 [END_TIME] => 3020020 [DURATION] => 4200 [TITLE] => Chapter 18 [DESCRIPTION] => Chapter 18\'s Description ) [7] => stdClass Object ( [ID] => 42 [COURSE_ID] => 4 [START_TIME] => 2858254 [END_TIME] => 2862309 [DURATION] => 4200 [TITLE] => Chapter 17 [DESCRIPTION] => Chapter 17\'s Description ) [8] => stdClass Object ( [ID] => 41 [COURSE_ID] => 4 [START_TIME] => 2703813 [END_TIME] => 2706641 [DURATION] => 4200 [TITLE] => Chapter 16 [DESCRIPTION] => Chapter 16\'s Description ) [9] => stdClass Object ( [ID] => 40 [COURSE_ID] => 4 [START_TIME] => 2551822 [END_TIME] => 2555208 [DURATION] => 4200 [TITLE] => Chapter 15 [DESCRIPTION] => Chapter 15\'s Description ) [10] => stdClass Object ( [ID] => 39 [COURSE_ID] => 4 [START_TIME] => 2382407 [END_TIME] => 2387901 [DURATION] => 4200 [TITLE] => Chapter 14 [DESCRIPTION] => Chapter 14\'s Description ) [11] => stdClass Object ( [ID] => 38 [COURSE_ID] => 4 [START_TIME] => 2225619 [END_TIME] => 2231232 [DURATION] => 4200 [TITLE] => Chapter 13 [DESCRIPTION] => Chapter 13\'s Description ) [12] => stdClass Object ( [ID] => 37 [COURSE_ID] => 4 [START_TIME] => 2064552 [END_TIME] => 2068656 [DURATION] => 4200 [TITLE] => Chapter 12 [DESCRIPTION] => Chapter 12\'s Description ) [13] => stdClass Object ( [ID] => 36 [COURSE_ID] => 4 [START_TIME] => 1913475 [END_TIME] => 1916306 [DURATION] => 4200 [TITLE] => Chapter 11 [DESCRIPTION] => Chapter 11\'s Description ) [14] => stdClass Object ( [ID] => 35 [COURSE_ID] => 4 [START_TIME] => 1750950 [END_TIME] => 1756908 [DURATION] => 4200 [TITLE] => Chapter 10 [DESCRIPTION] => Chapter 10\'s Description ) [15] => stdClass Object ( [ID] => 34 [COURSE_ID] => 4 [START_TIME] => 1587965 [END_TIME] => 1592709 [DURATION] => 4200 [TITLE] => Chapter 9 [DESCRIPTION] => Chapter 9\'s Description ) [16] => stdClass Object ( [ID] => 33 [COURSE_ID] => 4 [START_TIME] => 1431054 [END_TIME] => 1435008 [DURATION] => 4200 [TITLE] => Chapter 8 [DESCRIPTION] => Chapter 8\'s Description ) [17] => stdClass Object ( [ID] => 32 [COURSE_ID] => 4 [START_TIME] => 1280421 [END_TIME] => 1283872 [DURATION] => 4200 [TITLE] => Chapter 7 [DESCRIPTION] => Chapter 7\'s Description ) [18] => stdClass Object ( [ID] => 31 [COURSE_ID] => 4 [START_TIME] => 1123068 [END_TIME] => 1128464 [DURATION] => 4200 [TITLE] => Chapter 6 [DESCRIPTION] => Chapter 6\'s Description ) [19] => stdClass Object ( [ID] => 30 [COURSE_ID] => 4 [START_TIME] => 960918 [END_TIME] => 966370 [DURATION] => 4200 [TITLE] => Chapter 5 [DESCRIPTION] => Chapter 5\'s Description ) [20] => stdClass Object ( [ID] => 29 [COURSE_ID] => 4 [START_TIME] => 793943 [END_TIME] => 797123 [DURATION] => 4200 [TITLE] => Chapter 4 [DESCRIPTION] => Chapter 4\'s Description ) [21] => stdClass Object ( [ID] => 28 [COURSE_ID] => 4 [START_TIME] => 638285 [END_TIME] => 641130 [DURATION] => 4200 [TITLE] => Chapter 3 [DESCRIPTION] => Chapter 3\'s Description ) [22] => stdClass Object ( [ID] => 27 [COURSE_ID] => 4 [START_TIME] => 479384 [END_TIME] => 483993 [DURATION] => 4200 [TITLE] => Chapter 2 [DESCRIPTION] => Chapter 2\'s Description ) [23] => stdClass Object ( [ID] => 26 [COURSE_ID] => 4 [START_TIME] => 320101 [END_TIME] => 325435 [DURATION] => 4200 [TITLE] => Chapter 1 [DESCRIPTION] => Chapter 1\'s Description ) [24] => stdClass Object ( [ID] => 25 [COURSE_ID] => 4 [START_TIME] => 163844 [END_TIME] => 166828 [DURATION] => 2100 [TITLE] => Introductinon [DESCRIPTION] => A brief description of the course chapter's taken one by one along with the main notions and theories. ) ) ) )

回答1:

$data = array_change_key_case($data1,CASE_LOWER);

http://www.php.net/manual/en/function.array-change-key-case.php

来源：https://stackoverflow.com/questions/9315447/how-to-change-array-keys-from-uppercase-to-lowercase