My friend asked me a PHP-related question, so I ran to ask you!

My friend asked me a PHP question, but I didn't know it. so I ran to ask you !! I am engaged in JAVA, but my friend asked me a PHP question. the content is as follows: PHPcode $ testArrarray (php & gt; array (author & gt; allen, price & gt; 40,) a java friend asked me a PHP question. I don't know, so I ran to ask you !!
I am engaged in JAVA, but my friend asked me a PHP question. the content is as follows:

PHP code

  $testArr = array(    'php' => array(        'author' => 'allen',        'price' => 40,    ),    'java' => array(        'author' => 'james',        'price' => 55,    ),    'mysql' => array(        'author' => 'gates',        'price' => 30,    ),    'html' => array(        'author' => 'bill',        'price' => 21,    ));

How can I sort by price field ??
You can also use the library function !!

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Well, you are engaged in JAVA and the most expensive.

PHP code

Uasort ($ testArr, create_function ('$ a, $ B', 'return $ a ["price"]> $ B ["price"]; '); // change the price in ascending order to <
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PHP code
   
   
    Array ('author' => 'Allen ', 'price' => 40,), 'Java' => array ('author' => 'James ', 'price' => 55,), 'mysql' => array ('author' => 'gates', 'price' => 30 ,), 'html' => array ('author' => 'Bill ', 'price' => 21,); function my_sort ($ a, $ B) {return $ a ['price']> $ B ['price'];} uasort ($ testArr, "my_sort"); print_r ($ testArr);?>
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PHP code
     
     
Foreach ($ testArr as $ v) {$ k [] = $ v ['price'];} array_multisort ($ k, SORT_DESC, $ testArr ); print_r (array_slice ($ testArr, 0, 3 ));
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There are two types of three methods used by several persons upstairs.
Comparison:
      
      

       
       
PHP code
       
       
$ TestArr = array ('php' => array ('author' => 'Allen ', 'price' => 40 ,), 'Java' => array ('author' => 'James ', 'price' => 55 ,), 'mysql' => array ('author' => 'gates', 'price' => 30 ,), 'html' => array ('author' => 'Bill ', 'price' => 21 ,)); /*** application callback function ***/function func1 ($ ar) {uasort ($ ar, create_function ('$ a, $ B ', 'return $ a ["price"]> $ B ["price"]; '); // The price is in ascending order, in descending order, change to <}/*** do not use the callback function ***/function func2 ($ ar) {foreach ($ ar as $ key => $ row) {$ price [$ key] = $ row ['price'];} array_multisort ($ price, SORT_ASC, $ ar );} /*** application php5.3 closure ***/function func3 ($ ar) {array_multisort (array_map (function ($ v) {return $ v ['price'];}, $ ar), $ ar);} check_speed (200, 'function2', $ testArr); check_speed (200, 'func3', $ testArr); check_speed (200, 'function1', $ testArr );