array_key_exists

• This function’s solution uses a Ruby Hash object since Ruby arrays don’t use associative key/value pairs. See Array for more details.

  To check if a key exists in a Ruby hash, we can use Hash#include?.

  PHP

  $colors = array('orange' => 1, 'yellow' => 4);
  $result = array_key_exists('orange', $colors);
  var_export($result);
  // => true

  Ruby

  colors = {:orange => 1, :yellow => 4}  
  p colors.include?(:orange)
  # => true

  In PHP, we use array_key_exists instead of isset when it is important to know if a key actually exists, and is not just null. Hash#include? works similarly and will return true for a key even if it has a nil value.

  PHP

  $colors = array('orange' => 1, 'red' => null);
  $result = isset($colors['red']);
  var_export($result);
  // => false
   
  $result = array_key_exists('red', $colors);
  var_export($result);
  // => true

  Ruby

  colors = {:orange => 1, :red => nil}  
  p colors[:red]
  # => nil
   
  p colors.include?(:red)
  # => true

  see also

  • array_keys
  • array

Looking for Rails or PHP web application development, integration, and training?

Rails for PHP is brought to you by Maintainable Software. Get custom web applications and personalized training from the authors of the book and website.