Detailed explanation of how to get the array key name using php array_keys()

array_keys() Definition and usage

array_keys() FunctionReturns all key names in the array of a new 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 name with the specified value based on the type.
false - the default value. Does not depend on type.
Example 1

<?php 
$a=array("a"=>"Horse","b"=>"Cat","c"=>"Dog"); 
print
_r(array_keys($a)); 
?>

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

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

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

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

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

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

Output:
Array ( [0 ] => 3)

The above is the detailed content of Detailed explanation of how to get the array key name using php array_keys(). For more information, please follow other related articles on the PHP Chinese website!