The Ds\Deque::first() function is an inbuilt function in PHP which returns the first value in the Deque if Deque is not empty.
Syntax:
public Ds\Deque::first( void ) : mixed
Parameters: This function does not accept any parameter.
Return Value: This function returns the first element from the Deque, if the deque is not empty.
Below programs illustrate the Ds\Deque::first() function in PHP:
Program 1:
<?php // Declare a deque $deck = new \Ds\Deque([10, 20, 3, 40, 50, 6]); echo ( "Elements in the Deque\n" ); // Display the Deque elements print_r( $deck ); echo ( "\nFirst element in the deque: " ); // Use first() function to find // first element in the deque var_dump( $deck ->first()); ?> |
Elements in the Deque Ds\Deque Object ( [0] => 10 [1] => 20 [2] => 3 [3] => 40 [4] => 50 [5] => 6 ) First element in the deque: int(10)
Program 2:
<?php // Declare a deque $deck = new \Ds\Deque([ "Geeks" , "for" , "GFG" ]); echo ( "Elements in the Deque\n" ); // Display the Deque elements print_r( $deck ); echo ( "\nFirst element in the deque: " ); // Use first() function to find // first element in the deque var_dump( $deck ->first()); ?> |
Elements in the Deque Ds\Deque Object ( [0] => Geeks [1] => for [2] => GFG ) First element in the deque: string(5) "Geeks"
Reference: http://php.net/manual/en/ds-deque.first.php