What does the PHP syntax $var1
以下语法的解释是什么？
$var1->$var2 // Note the second $
$var1 is an object.
$var2 is (possibly) the name of a variable inside $var1 .
If $var2="test"; this is evaluated to:
$var1->test;
You can do this with all sorts of things:
$test = array();
$name="test";
print_r($$name); // Prints array();
$test = new stdClass;
$test->hello = "hi";
$name2="hello";
echo $test->$name2; // Echos hi
You can even get really fancy:
echo $$name->$name2; // Echos hi
It means dynamically query a property in an object.
class A {
public $a;
}
// static property access
$ob = new A;
$ob->a = 123;
print_r($ob);
// dynamic property access
$prop = 'a';
$ob->$prop = 345; // effectively $ob->a = 345;
print_r($ob);
so $var1 is an instance of some object, -> means access to a member of that object and $var2 contains the name of a property.
上一篇: >“意味着/指在PHP中？
下一篇: PHP语法$ var1是什么？