# Pre-Processor Directives
**The code below** is called a **preprocessor directive** and is only valid if the build is for **Android** or **iOS** platform or else the compiler will ignore this code
```csharp
#if PLATFORM_ANDROID
using UnityEngine.Android;
#elif UNITY_IOS
using UnityEngine.iOS;
#endif
```
[C# preprocessor directives | Microsoft Docs](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/preprocessor-directives/)
I could make 2 separate scripts, 1 for Windows & 1 for Android, but since most of the code is similar instead of repeating myself I can just implement a preprocessor directive. To see what preprocessor directives are in your Unity Project you can go to ***`File/Build Settings/Player Settings/Player/Other Settings/Scripting Define Symbols`*** ***This doesn't list every available preprocessor directive, such as the***** `PLATFORM_ANDROID` ****shown above**
or
***`Edit/Project Settings/Player/Other Settings/Scripting Define Symbols`***
