如何在PHP中打印类的项目？

Question

I have this class:

class MyClass {
    public $dummy = array('foo', 'bar', 'baz', 'qux');
    public $progr = array('HTML', 'CSS', 'JS', 'PHP');
}

I'm trying to print that out: print_r(MyClass) , but it outputs MyClass and nothing else. I get similiar things with echo , print , var_dump and var_export . It seems that they treat MyClass as a string, because echo(test) outputs test .

So, how can I list the items of a class?

Answer 1

Use ReflectionClass on an instance of your class, and optionally use ReflectionProperty to get the values of the properties as in your instance:

$rc = new ReflectionClass(new MyClass());

foreach ($rc->getProperties() as $property) {
    printf('%s = %s', $property->getName(), print_r($property->getValue(), true));
}

On second thought, if you just want to get the values of an object's properties then mingos' answer using print_r(new MyClass()); works too.

Another thing,

It seems that they treat MyClass as a string, because echo(test) outputs test .

This is normal: PHP first treats them as constant names, but if it can't find constants defined with those names, then it treats them as unquoted string literals.

Answer 2

Have you instantiated it?

What does this output:

$m = new MyClass();
print_r($m);

Answer 3

Sometimes it can be helpful to implement the class's __toString magic method as well. In brief, __toString allows you to specify exactly how an object should behave when it is echoed. For more information, please see the following:

http://www.php.net/manual/en/language.oop5.magic.php#language.oop5.magic.tostring

I like to use __toString as a debugging tool, though I'm sure the true potential of the method is significantly more profound :)

Hope that helps.

Answer 4

http://php.net/manual/en/class.reflectionclass.php和print_r（）;