數組array集合

一、比較兩個數組之差：array_diff
例如：
$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("e"=>"red","f"=>"green","g"=>"blue");
$result=array_diff($a1,$a2);
print_r($result);
結果為：Array ( [d] => yellow )

二、比較兩個數組的交集：array_intersect
例如：
$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("e"=>"red","f"=>"green","g"=>"blue");
$result=array_intersect($a1,$a2);
print_r($result);
結果為：Array ( [a] => red [b] => green [c] => blue )

三、取出數組中的那些數據：array_slice
array_slice默認是不保留鍵名的。
使用array_slice函數要保留鍵名值，最后一個參數$preserve_keys設置為true即可。
例如：
$levels = array('a' => 1, 'b' =>2, 'c' => 3, 'd' => 4, 'f' => 5, 'g' => 6);
$firstLevels = array_slice($levels, 0, 5, true);
結果為：
$firstLevels = array('a' => 1, 'b' =>2, 'c' => 3, 'd' => 4, 'f' => 5);

四、合并數組：array_merge()
例如：
$a1=array("red","green");
$a2=array("blue","yellow");
print_r(array_merge($a1,$a2));
結果為：Array ( [0] => red [1] => green [2] => blue [3] => yellow )

五、取出二維數組中的某個字段：array_column()
例如：
$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');
print_r($last_names);

結果為：
Array
(
[0] => Griffin
[1] => Smith
[2] => Doe
)

六、將數組一維數組分成二維數組： array_chunk()
例如：
$cars=array("Volvo","BMW","Toyota","Honda","Mercedes","Opel");
print_r(array_chunk($cars,2));

結果為：
Array (
[0] => Array (
[0] => Volvo
[1] => BMW
)
[1] => Array (
[0] => Toyota
[1] => Honda
)
[2] => Array (
[0] => Mercedes
[1] => Opel
)
)