Types, Comparisons, and Values

Core PHP Types

Type	Example	Notes
int	42	Whole number
float	3.14	Decimal number
string	'hello'	Text or binary-safe byte string
bool	true	Boolean value
array	['a', 'b']	Ordered map
object	$post	Class instance
null	null	No value
resource	File handle	Legacy external resource handle

Type Checks

is_int($value);
is_float($value);
is_string($value);
is_bool($value);
is_array($value);
is_object($value);
is_null($value);
is_numeric($value);

Casting

$id = (int) $raw_id;
$price = (float) $raw_price;
$label = (string) $raw_label;
$enabled = (bool) $raw_enabled;
$items = (array) $raw_items;

In WordPress, prefer semantic normalizers when available.

$post_id = absint($_GET['post_id'] ?? 0);
$key = sanitize_key($_GET['key'] ?? '');

Truthy and Falsy

Falsy values include false, 0, 0.0, '', '0', [], and null. Everything else is truthy.

if ($value) {
    // Runs for truthy values.
}

Be careful with saved options that may legitimately be '0'.

Loose vs Strict Comparison

Expression	Meaning
$a == $b	Equal after type coercion
$a === $b	Equal and same type
$a != $b	Not equal after type coercion
$a !== $b	Not equal or different type

Prefer strict comparison.

if (false === get_option('myplugin_missing_value')) {
    // Option does not exist.
}

Null Coalescing and Ternary

$value = $array['key'] ?? 'default';
$label = $enabled ? 'Enabled' : 'Disabled';

Avoid ternary shorthand when 0, '0', or '' are valid values.

Typed Parameters and Returns

function myplugin_format_count(int $count): string {
    return number_format_i18n($count);
}

PHP 8+ supports union types.

function myplugin_normalize_id(int|string $raw_id): int {
    return absint($raw_id);
}

Use only when the target PHP version supports it.

WordPress Return Value Patterns

API Pattern	Example	How To Check
false on missing	get_option()	false === $value
WP_Error on failure	wp_remote_get()	is_wp_error($value)
0 on missing ID	get_current_user_id()	0 === $user_id
Empty array	get_posts()	[] === $posts
Object or null	get_post()	$post instanceof WP_Post

Common WordPress Type Normalizers

Input Goal	Function
Positive integer	absint()
Key or slug	sanitize_key()
Text	sanitize_text_field()
Textarea	sanitize_textarea_field()
Email	sanitize_email()
URL for storage	esc_url_raw()
Boolean checkbox	! empty($value)

Checking Arrays and Objects

$settings = get_option('myplugin_settings', []);

if (! is_array($settings)) {
    $settings = [];
}

$limit = isset($settings['limit']) ? absint($settings['limit']) : 10;

$post = get_post($post_id);

if (! $post instanceof WP_Post) {
    return;
}

empty, isset, array_key_exists

Function	Behavior
isset($x)	False if missing or null
empty($x)	True if missing or falsy
array_key_exists('k', $a)	True if key exists, even null

Production Checklist

• Use strict comparisons for sentinel values like false.
• Normalize IDs with absint().
• Confirm arrays are arrays before reading nested keys.
• Check WP_Error before reading HTTP or media responses.
• Avoid truthiness when 0 or empty string are valid values.
• Do not add modern type syntax unless production PHP supports it.