PHP Arrays Storing Multiple Elements per Key in an Array

PHP Arrays

Storing Multiple Elements per Key in an Array

Problem

You want to associate multiple elements with a single key.

Solution

Store the multiple elements in an array:

              $fruits = array('red' => array('strawberry','apple'),
                                      'yellow' => array('banana'));

Or use an object:
   
              while ($obj = mysqli_fetch_assoc($r)) {
                     $fruits[] = $obj;
              }

Discussion

In PHP, keys are unique per array, so you can’t associate more than one entry in a key without overwriting the old value. Instead, store your values in an anonymous array:

              $fruits = array();
              $fruits['red'][] = 'strawberry';
              $fruits['red'][] = 'apple';
              $fruits['yellow'][] = 'banana';

              print_r($fruits);

This prints:

              Array
              (
                      [red] => Array
                            (
                                    [0] => strawberry
                                    [1] => apple
                            )
                      [yellow] => Array
                            (
                                    [0] => banana
                            )
              )

Or, if you’re processing items in a loop:

              while (list($color,$fruit) = mysqli_fetch_assoc($r)) {
                      $fruits[$color][] = $fruit;
              }

To print the entries, loop through the array:

              foreach ($fruits as $color => $color_fruit) {
                      // $color_fruit is an array
                      foreach ($color_fruit as $fruit) {
                            print "$fruit is colored $color.<br>";
                      }
              }

Or use the array_to_comma_string() function:

              foreach ($fruits as $color => $color_fruit) {
                      print "$color colored fruits include " .
                            array_to_comma_string($color_fruit) . "<br>";
              }