PHP数组使用

php删除数组首个元素
$a=array("a"=>"red","b"=>"green","c"=>"blue");
echo array_shift($a);
print_r ($a);
red        Array ( [b] => green [c] => blue )


合并数组
$a1=array('a'=>'aaa');
$a2=array('b'=>'bbb');
dd(array_merge($a1,$a2));
array:2 [▼
  "a" => "aaa"
  "b" => "bbb"
]


返回所有的key
$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");
dd(array_keys($a));
array:3 [▼
  0 => "Volvo"
  1 => "BMW"
  2 => "Toyota"
]


返回所有value
$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");
dd(array_values($a));
array:3 [▼
  0 => "XC90"
  1 => "X5"
  2 => "Highlander"
]


array_filter使用
$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];

var_dump(array_filter($arr, function($value) {
    return $value == 4;
}));

var_dump(array_filter($arr, function($k) {
    return $k == 'b';
}, ARRAY_FILTER_USE_KEY));

var_dump(array_filter($arr, function($v, $k) {
    return $k == 'b' || $v == 4;
}, ARRAY_FILTER_USE_BOTH));


array_change_key_case使用
$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
$a=array_change_key_case($arr,CASE_UPPER);
dd($a);
array:4 [▼
  "A" => 1
  "B" => "b"
  "C" => 3
  "D" => 4
]

array_chunk分割数组
$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
$a2=array_chunk($arr,2,true);//第三个参数默认false返回value，ture返回整个数组
dd($a2);
array:2 [▼
  0 => array:2 [▼
    "a" => 1
    "b" => 2
  ]
  1 => array:2 [▼
    "c" => 3
    "d" => 4
  ]
]


array_column 取数组一列
$records = array(
    array(
        'id' => 2135,
        'first_name' => 'John',
        'last_name' => 'Doe',
    ),
    array(
        'id' => 3245,
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ),
    array(
        'id' => 5342,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ),
    array(
        'id' => 5623,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    )
);
$first_names = array_column($records, 'first_name');
dd(implode(',',$first_names));
输出:"John,Sally,Jane,Peter"


array_combine 合并数组，key,value方式合并
$a = array('green', 'red', 'yellow');
$b = array('avocado', 'apple', 'banana');
$c = array_combine($a, $b);
print_r($c);

Array ( [green] => avocado [red] => apple [yellow] => banana )


array_flip互换key和value
$input = array("a" => 1, "b" => 1, "c" => 2);
$flipped = array_flip($input);
dd($flipped);
array:2 [▼
  1 => "b"
  2 => "c"
]

array_map用法
$a = array(1, 2, 3, 4, 5);
$b = array("uno", "dos", "tres", "cuatro", "cinco");
dd(array_map(
    function($k,$v){
        return("The number $k  is called $v in Spanish");
    },$a,$b
));
$c =array_combine($a,$b);
array:5 [▼
  0 => "The number 1  is called uno in Spanish"
  1 => "The number 2  is called dos in Spanish"
  2 => "The number 3  is called tres in Spanish"
  3 => "The number 4  is called cuatro in Spanish"
  4 => "The number 5  is called cinco in Spanish"
]