Array
(
    [d] => lemon
    [a] => orange
    [b] => banana
    [c] => apple
)



 arsort Sort an array in reverse order and maintain index association

a = orange
d = lemon
b = banana
c = apple



 asort Sort an array and maintain index association

c = apple
b = banana
d = lemon
a = orange



 krsort Sort an array by key in reverse order

d = lemon
c = apple
b = banana
a = orange



 ksort Sort an array by key

a = orange
b = banana
c = apple
d = lemon



 rsort Sort an array in reverse order

0 = orange
1 = lemon
2 = banana
3 = apple



 sort Sort an array

0 = apple
1 = banana
2 = lemon
3 = orange



 natsort Sort an array using a "natural order" algorithm

 Standard sorting

Array
(
    [0] => img1.png
    [1] => img10.png
    [2] => img12.png
    [3] => img2.png
)

 Natural order sorting

Array
(
    [3] => img1.png
    [2] => img2.png
    [1] => img10.png
    [0] => img12.png
)



 array_unique Removes duplicate values from an array

Array
(
    [a] => green
    [0] => red
    [b] => green
    [1] => blue
    [2] => red
)

 Example #1 array_unique() example

Array
(
    [a] => green
    [0] => red
    [1] => blue
)

 Example #2 array_unique() and types

array(2) {
  [0]=>
  int(4)
  [2]=>
  string(1) "3"
}



 print_r and var_dump

Array
(
    [0] => apple
    [1] => banana
    [2] => lemon
    [3] => orange
)

array(4) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(6) "banana"
  [2]=>
  string(5) "lemon"
  [3]=>
  string(6) "orange"
}