arraylist namespace php array function sequence array_keys - get array key name

array_keys() Definition and Usage
array_keys() function returns a new array containing all the key names in the array.
If the second parameter is provided, only the key name with the key value is returned.
If the strict parameter is specified as true, PHP will use equality comparison (===) to strictly check the data type of the key value.
Syntax
array_keys(array,value)
Parameter Description
array Required. Specifies the input array.
value optional. The index (key) of the specified value.
strict optional. Used with the value parameter. Possible values:
true - Returns the key with the specified value based on the type.
false - default value. Does not depend on type.
Example 1

Copy the code The code is as follows:

$a=array("a"=>"Horse","b"=>"Cat","c" =>"Dog");
print_r(array_keys($a));
?>

Output:
Array ( [0] => a [1] => b [2] => c)
Example 2
Use value parameter:

Copy the code The code is as follows:

$a=array("a"=>"Horse","b"=> "Cat","c"=>"Dog");
print_r(array_keys($a,"Dog"));
?>

Output:
Array ( [0] => c)
Example 3
Use strict parameter (false):

Copy code The code is as follows:

$a=array(10,20,30,"10");
print_r(array_keys( $a,"10",false));
?>

Output:
Array ( [0] => 0 [1] => 3 )
Example 4
Use strict parameter (true):

Copy code The code is as follows:

$a=array(10,20,30,"10");
print_r(array_keys($a,"10",true));
?>

Output:
Array ( [0] => 3)

The above introduces the array_keys of the arraylist namespace PHP array function sequence - getting the array key name, including the content of the arraylist namespace. I hope it will be helpful to friends who are interested in PHP tutorials.