(PHP 5 >= 5.1.2, PHP 7, PHP 8)
ReflectionClass::hasProperty — Checks if property is defined
$name): boolChecks whether the specified property is defined.
nameName of the property being checked for.
   true if it has the property, otherwise false
  
Example #1 ReflectionClass::hasProperty() example
<?php
class Foo {
    public    $p1;
    protected $p2;
    private   $p3;
}
$obj = new ReflectionObject(new Foo());
var_dump($obj->hasProperty("p1"));
var_dump($obj->hasProperty("p2"));
var_dump($obj->hasProperty("p3"));
var_dump($obj->hasProperty("p4"));
?>
The above example will output something similar to:
bool(true) bool(true) bool(true) bool(false)