Are PHP namespaces used with a leading slash

Question

When using PHP namespaces, do you use them like:

\Foo\Bar->method()

or

Foo\Bar->method()

Notice the difference is only a leading slash. Or are both valid, and mean different things?

Thanks.

Answer 1

The usage of a leading \ is like absolute and relative paths in filesystems. Best explained with code:

namespace test;
$dt = new DateTime();

fails, as we are using an relative path (without the leading \), and the current namespace test. And there is not class DateTime in this fictional namespace.

namespace test;
$dt = new \DateTime();

works as we are using an absolute namespaces path. As DateTime is in the global namespace \ it will be found.

Find more info in the PHP manual about namespaces