分享六个比较好用的php数组Array函数

// 可能从数据库中返回数组
$a = array(
 array(
  'id' => 5698,
  'first_name' => 'Peter',
  'last_name' => 'Griffin',
 ),
 array(
  'id' => 4767,
  'first_name' => 'Ben',
  'last_name' => 'Smith',
 ),
 array(
  'id' => 3809,
  'first_name' => 'Joe',
  'last_name' => 'Doe',
 )
);
$last_names = array_column($a, 'last_name', 'id');
print_r($last_names);

function test_odd($var)
{
  return($var & 1);
}
$a1=array("a","b",2,3,4);
print_r(array_filter($a1,"test_odd"));

 function myfunction($v) {
   if (is_array($v)) {
     return array_map("myfunction", $v);
   }
  return($v * $v);
} 
 $a = array(1, 2, 3, 4, 5, 6 => [2, 3]);
print_r(array_map("myfunction", $a));

 function myfunction($v1, $v2) {
  if ($v1 === $v2) {
     return "same";
   }
   return "different";
 } 
 $a1 = array("Horse", "Dog", "Cat");
 $a2 = array("Cow", "Dog", "Rat");
 print_r(array_map("myfunction", $a1, $a2));

 function myfunction(&$value, $key, $p) {
   if ($value == 'xxx') {
     $value = $p;
   }
 }
 $a = array("a" => "red", "b" => "green", "c" => "blue", 'd' => ['x' => 'xxx', 'y' => 'yyy']);
 array_walk_recursive($a, "myfunction", 'green');
 print_r($a);

 $a = "Original";
$my_array = array("a" => "Cat","b" => "Dog", "c" => "Horse");
 extract($my_array);
 echo "\$a = $a; \$b = $b; \$c = $c";

 $firstname = "Peter";
 $lastname = "Griffin";
 $age = "41";
$result = compact("firstname", "lastname", "age");
 print_r($result);

$arr2 = [
  [
    'id' => 3,
    'age' => 33,
  ],
  [
    'id' => 2,
    'age' => 44,
  ],
  [
    'id' => 1,
    'age' => 22,
  ],
];
//按age字段升序排序
uasort($arr2, function($a, $b) {
  $field = 'age';
  if ($a[$field] == $b[$field]){
    return 0;
  }
  return ($a[$field] < $b[$field]) ? -1 : 1;
});
print_r($arr2);