Title: Sequential selection from array
Last modified: March 4, 2019

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# Sequential selection from array

 *  Resolved [nad33m](https://wordpress.org/support/users/nad33m/)
 * (@nad33m)
 * [7 years, 3 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/)
 * This code gets a letter ($letter) from the array ($alphabet) randomly. This PHP
   is at the top of the functions.php file in WordPress and gets used in an action
   to echo the $letter in an email when an order is placed in woo.
 * How do I change the code so $letter holds the next letter each time the action
   is is called? So the 1st email echos ‘a’ , 2nd email ‘b’ e.t.c.
 *     ```
       $alphabet = array ('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h' );
   
       $rand_keys = array_rand($alphabet, 1);
   
       $letter = $alphabet[$rand_keys] . "\n";
       ```
   
 * Thank you in advance.
    -  This topic was modified 7 years, 3 months ago by [nad33m](https://wordpress.org/support/users/nad33m/).
    -  This topic was modified 7 years, 3 months ago by [nad33m](https://wordpress.org/support/users/nad33m/).

Viewing 6 replies - 1 through 6 (of 6 total)

 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [7 years, 3 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11274371)
 * The next available index needs to be stored somewhere. I assume this value needs
   to persist over multiple requests over an extended period of time, and that the
   value is to be globally applied site wide (not per user or per order). One place
   to save such a value is in the options table. Use update_option() and get_option()
   to save and retrieve the saved value.
 * Naturally you need code to reset the index to zero once it uses the last element
   in the array.
 *  Thread Starter [nad33m](https://wordpress.org/support/users/nad33m/)
 * (@nad33m)
 * [7 years, 3 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11276212)
 * [@bcworkz](https://wordpress.org/support/users/bcworkz/) thanks, I have thought
   about doing it this way, need help advancing the pointer, and return to zero 
   when at the end of the array:
 * `add_option( 'last-letter-key', 0 ) <--Adds new database variable -->`
 *     ```
       $last_key = get_option( 'last-letter-key' );  <--Retrieves last key from database -->
   
       $letter = $alphabet[$last_key];  <--sets letter using $last_key -->
   
       $letter = next($alphabet); <-- advances to next name -->
   
       <---here is where I think I need to put a loop to advance the pointer, what code goes here? -->
   
       $last_key = key($alphabet); <-- gets new key that is +1 now -->
   
       update_option( 'last-letter-key', $last_key ); <--saves new key to database -->
       ```
   
    -  This reply was modified 7 years, 3 months ago by [nad33m](https://wordpress.org/support/users/nad33m/).
    -  This reply was modified 7 years, 3 months ago by [nad33m](https://wordpress.org/support/users/nad33m/).
 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [7 years, 3 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11277959)
 * Unless you know otherwise, I don’t think there is an easy way to directly set
   the internal pointer to a particular value, so using next() is not an effective
   way to get the next available letter. No problem, array elements can be accessed
   directly, like so:
    `$letter = $alphabet[$last_key+1];`
 * Before doing that though, check `if ( $last_key+1 == count( $alphabet ))`. If
   it is, the end of the alphabet has been reached and $last_key needs to be reset
   to -1 so when we add 1 to it, it gets the first element in the array at index
   0.
 * You see, we are not using the internal pointer at all now. Instead, we are keeping
   track of the last array index used. No looping is required. Yes, you could reset
   the internal pointer, then do a loop of $last_key calls to next() to get to the
   right place, but there is no need. After getting the next letter from $alphabet,
   update the option to `$last_key+1`
 * Also, you don’t really need to initialize the option with add_option(). update_option()
   will add it if it does not already exist. So you start off your code with getting
   the option. We don’t yet know if it even exists at first, but we try to get it
   anyway.
 * Next, check `if ( false === $last_key )`. If so, there is no saved value so initialize
   $last_key to -1, again so when we add 1 to it we get the first array value. To
   summarize:
    get the option if false comes back, set $last_key to -1 if $last_key
   has reached the alphabet end, reset $last_key back to -1 Assign to $letter the
   value extracted from $alphabet update the option return $letter
 *  Thread Starter [nad33m](https://wordpress.org/support/users/nad33m/)
 * (@nad33m)
 * [7 years, 3 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11278611)
 * [@bcworkz](https://wordpress.org/support/users/bcworkz/) Thank you so much. The
   part about not needing the internal pointer now makes it simpler. With your answer
   I am confident I can now write the new code. I will report back with results 
   and my final code.
 *  Thread Starter [nad33m](https://wordpress.org/support/users/nad33m/)
 * (@nad33m)
 * [7 years, 2 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11327315)
 *     ```
       function getNextLetter(){
       	$alphabet = array ('A', 'B', 'C, 'D');
   
       	$letterKey = LetterKey;
       	$recIndex = 0;
       	if(get_option( $letterKey ) !== false){
       		$recIndex = get_option( $letterKey );
       		$updateNextIndex = ($recIndex+1) < count($alphabet) ? ($recIndex+1) : 0;
       		update_option($letterKey, $updateNextIndex);
       		return $alphabet[$recIndex];
       	}else{
       		add_option($letterKey, 1);
       		return $alphabet[$recIndex];
       	}
       }
       ```
   
 * So I got it to work using the above code, each time the function is called it
   returns the next letter, and starts from the beginning when it returns the last
   letter.
 * $letterKey is stored in the database, which holds the last letter position.
 * Hope that will help anyone needing similar code. Probably could of been coded
   more elegantly, but it works, so my problem is solved.
 * A big thank you to bcworkz for pointing me in the right direction.
 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [7 years, 2 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11331347)
 * Nicely done! You’re most welcome.

Viewing 6 replies - 1 through 6 (of 6 total)

The topic ‘Sequential selection from array’ is closed to new replies.

 * In: [Developing with WordPress](https://wordpress.org/support/forum/wp-advanced/)
 * 5 replies
 * 2 participants
 * Last reply from: [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * Last activity: [7 years, 2 months ago](https://wordpress.org/support/topic/sequential-selection-from-array/#post-11331347)
 * Status: resolved

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