php constant can be referenced but defined() returns false

Question

Has anyone encountered this? ``` var_dump(CRYPT_SHA256 == 1); // returns bool(true) var_dump(defined(CRYPT_SHA256)); // returns bool(false) ```

Accepted Answer

Add quotation marks

```
defined('CRYPT_SHA256')
```

Otherwise, you are asking whether the value of the `CRYPT_SHA256` constant is also the name of another constant....

```
defined(CRYPT_SHA256) === defined('1');
```

Edit : Add namespace

If your constant is defined in a namespace, you must include it in the constant name.

```
namespace Some\Namespace;

const MY_CONST = 'value';

var_dump( defined('MY_CONST') ); // false unless another constant has been defined
var_dump( defined('Some\Namespace\MY_CONST'); // true
```

This is not the case in the original question, but it can be a cause of the same problem too.

Solution