# Ptr

This type is a literal pointer.

To preserve interoperability with C++, several functions return `void*` as the type, which then get converted to `light_userdata`. Since you can’t directly cast FFI types to `light_userdata`, we’ve introduced a specialized type helping with this conversion.

Before you convert your pointer to one that is supported by the API, you need to cast it to `uintptr_t`. This can be done in the following manner:

```lua
local ptr_num = ffi.cast('uintptr_t', ptr_cdata);
```

Then, you can use the cast value in this type's constructor.

## \_\_call <a href="#call" id="call"></a>

[<kbd><mark style="background-color:purple;">**Constructor**<mark style="background-color:purple;"></kbd>](#user-content-fn-1)[^1]

Converts a number to pointer.

**Arguments**

| Name  | Type  | Description         |
| ----- | ----- | ------------------- |
| `num` | `int` | Pointer, as number. |

**Returns**

| Type  | Description                   |
| ----- | ----------------------------- |
| `Ptr` | Pointer, as `light_userdata`. |

**Example**

```lua
-- cast to number first
local ptr_num = ffi.cast('uintptr_t', ptr_cdata);

-- then cast to light_userdata
local ptr_ld = Ptr(ptr_num);
```

[^1]: This is a constructor definition for this type.


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