Analysis of multi-dimensional array sorting algorithm implemented by PHP

In this paper, we describe the multi-dimensional array sorting algorithm implemented by PHP. Share to everyone for your reference, as follows:

Suddenly think of an interview question, a multidimensional array sort.

Cases:

<?php//has a multidimensional array of $ A = Array ('  key1 ' =>940, ' key2 ' = ' blah '),  array (' Key1 ' =>23, ' key2 ' = ') This '),  array (' Key1 ' =>894, ' key2 ' = ' that ')), or//So how to sort key1 or key2, here you need to use Usort ($arr, ' myfunction ') function, it is the role of $arr using our custom method to sort, the use of the method can be viewed in the manual//1. Sort the values of Key1 function Asc_key1_sort ($x, $y) {  //You can output it and see how it compares.  Echo ' iteration: '. $x [' Key1 ']. ' vs '. $y [' Key1 '];  if ($x [' Key1 '] > $y [' key1 ']) {    echo ' true<br/> ';    return true;  } ElseIf ($x [' Key1 '] < $y [' Key1 ']) {    echo ' false<br/> ';    return false;  } else {    echo ' 0 ';    return 0;}  } Sort Usort ($a, ' asc_key1_sort '); Var_dump ($a);//2. Sort Key2 characters Function asc_key2_sort ($x, $y) {  // You can use the strcasecmp () function to sort  echo ' iteration: '. $x [' Key2 ']. ' vs '. $y [' Key2 ']. ' <br/> ';  return strcasecmp ($x [' Key2 '], $y [' Key2 ']);} Sort Usort ($a, ' asc_key2_sort '); Var_dump ($a);? >

Operation Result:

Iteration:23 vs 940falseiteration:894 vs 23trueiteration:940 vs 23trueiteration:894 vs 940falsearray (3) {[0]=> Array ( 2) {["Key1"]=> int () ["Key2"]=> string (4) "This"} [1]=> Array (2) {["Key1"]=> Int (894) ["Key2"]=> Strin G (4) "that"} [2]=> Array (2) {["Key1"]=> int (940) ["Key2"]=> string (4) "Blah"}} iteration:that vs Thisiteratio N:blah vs Thatarray (3) {[0]=> Array (2) {["Key1"]=> int (940) ["Key2"]=> string (4) "Blah"} [1]=> Array (2) {[ "Key1"]=> Int (894) ["Key2"]=> string (4) "that"} [2]=> Array (2) {["Key1"]=> Int (23°c) ["Key2"]=> string (4) " This "}}

What if I have a key value in my multidimensional array?

<?php//has a multidimensional array of $ A = Array (123 = = Array (  ' Key1 ' =>940, ' key2 ' = ' blah '), 349 = =  Array (' key1 ' = The ' key2 ' = ' this '), the  [' Key1 ' =>894, ' key2 ' = ' that '), and/or so how to sort key1 or Key2, This requires the use of the Usort ($arr, ' myfunction ') function, which is used to sort the $arr using our own custom methods, which can be used to view the manual//1. Sort the values of Key1 function Asc_key1_sort ( $x, $y) {  //can output a bit to see how it compares the  echo ' iteration: '. $x [' Key1 ']. ' vs '. $y [' Key1 '];  if ($x [' Key1 '] > $y [' key1 ']) {    echo ' true<br/> ';    return true;  } ElseIf ($x [' Key1 '] < $y [' Key1 ']) {    echo ' false<br/> ';    return false;  } else {    echo ' 0 ';    return 0;}  } Sort Usort ($a, ' asc_key1_sort '); Var_dump ($a);//2. Sort Key2 characters Function asc_key2_sort ($x, $y) {  // You can use the strcasecmp () function to sort  echo ' iteration: '. $x [' Key2 ']. ' vs '. $y [' Key2 ']. ' <br/> ';  return strcasecmp ($x [' Key2 '], $y [' Key2 ']);} Sort Usort ($a, ' asc_key2_sort '); Var_dump ($a);? >

Operation Result:

Iteration:23 vs 940falseiteration:894 vs 23trueiteration:940 vs 23trueiteration:894 vs 940falsearray (3) {[0]=> Array ( 2) {["Key1"]=> int () ["Key2"]=> string (4) "This"} [1]=> Array (2) {["Key1"]=> Int (894) ["Key2"]=> Strin G (4) "that"} [2]=> Array (2) {["Key1"]=> int (940) ["Key2"]=> string (4) "Blah"}} iteration:that vs Thisiteratio N:blah vs Thatarray (3) {[0]=> Array (2) {["Key1"]=> int (940) ["Key2"]=> string (4) "Blah"} [1]=> Array (2) {[ "Key1"]=> Int (894) ["Key2"]=> string (4) "that"} [2]=> Array (2) {["Key1"]=> Int (23°c) ["Key2"]=> string (4) " This "}}

Such sorting results are not retained for 123,349, 43. It's just a good time to usort() change uasort it!