array_fill_keys(): Fill array with values and keys

$new_array = array_fill_keys ($keys_array, $value);

Example with two arrays

$keys=array('One' ,'Two','Three','Four');
$input='First';

$result=array_fill_keys($keys,$input);
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

One -> First 
Two -> First 
Three -> First 
Four -> First 

Example 2

$keys=array('One' ,2,'3','F');
$input='First';

$result=array_fill_keys($keys,$input);
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

One -> First 
2 -> First 
3 -> First 
F -> First

Example 3 : Using associative array

$keys=array('One' ,'Two','Three');
$input=array('First','Second');
$result=array_fill_keys($keys,$input);
print_r($result);

Array ( 
  [One] => Array ( [0] => First [1] => Second )
  [Two] => Array ( [0] => First [1] => Second )
  [Three] => Array ( [0] => First [1] => Second )
  )

Example 4: Initializing a Configuration Array

$config_keys = ['timezone', 'language', 'currency'];
$default_values = array_fill_keys($config_keys, 'default_value');
print_r($default_values);
// Output: Array ( [timezone] => default_value [language] => default_value [currency] => default_value )

Example 5: Placeholder Array with Empty Values

$keys = ['name', 'email', 'phone'];
$placeholders = array_fill_keys($keys, '');
print_r($placeholders);
// Output: Array ( [name] => [email] => [phone] => )

Example 6: Generating a Grid with Default Values

$grid_keys = range(1, 100);
$grid = array_fill_keys($grid_keys, 0);
print_r($grid);
// Output: Array ( [1] => 0 [2] => 0 ... [100] => 0 )