一眼看懂 php 数组函数 array_key_exists

 //实例
array_key_exists($platformNum, $arrPlatform)
$a=array("name"=>"caoss","age"=>"21");
if (key_exists("name",$a))
  {
  echo "键存在！";
  }
else
  {
  echo "键不存在！";
  }
//输出   键存在！  索引数组也可是查数字
$a=array("name"=>"caoss","age"=>"21");
if (key_exists("Toyota",$a))
  {
  echo "键存在！";
  }
else
  {
  echo "键不存在！";
  }
//输出   键不存在！

$fruit=array("苹果","香蕉");  关联数组示例 $fruit=array(‘orange‘=>‘橘子‘，‘apple‘=>‘苹果‘);

//实例
$a = array(
  array(
    ‘id‘ => 5698,
    ‘first_name‘ => ‘Bill‘,
    ‘last_name‘ => ‘Gates‘,
  ),
  array(
    ‘id‘ => 4767,
    ‘first_name‘ => ‘Steve‘,
    ‘last_name‘ => ‘Jobs‘,
  )
  array(
    ‘id‘ => 3809,
    ‘first_name‘ => ‘Mark‘,
    ‘last_name‘ => ‘Zuckerberg‘,
  )
);

$last_names = array_column($a, ‘last_name‘, ‘id‘); 
print_r($last_names);

//结果 
Array
(
  [5698] => Gates
  [4767] => Jobs
  [3809] => Zuckerberg
)