Add field to entity programmatically in Drupal 7

Source code viewer
field_create_field(array(
  'field_name' => 'field1',
  'cadinality' => 1,
  'type' => 'number_integer', //number_decimal, text_long, text
));
field_create_instance(array(
  'field_name' => 'field1',
  'label' => 'this is an instance for field 1',
  'entity_type' => 'imported_tables',
  'bundle' => 'bundle_name',
));
Programming Language: PHP