UnrealEngineUWP/Engine/Documentation/Source/Programming/QuickStart/3/QuickStart_3.INT.udn

Availability: Public
Title:3 - Write and Compile C++ Code
Crumbs:%ROOT%, Programming, Programming/QuickStart
Description:Writing a C++ class and compiling it with Unreal Engine
SkillLevel: Beginner
Version: 4.9

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%Steps%

1. In **Visual Studio**, we'll use the **Solution Explorer** pane to find our newly-created C++ files. In our example, they will be named `FloatingActor.cpp` and `FloatingActor.h` and will be inside the "QuickStart" project.

	[![](SolutionExplorer_Files.png)](SolutionExplorer_Files.png)

	[REGION:note]We're about to write code. All code used in this tutorial will be found at bottom of the page in its current state as of completing that page's instructions.[/REGION]

1. In `FloatingActor.h`, we'll add the following code just before the closing brace and semicolon at the end of the file:

		float RunningTime;

1. Switching to `FloatingActor.cpp`, we'll add the following code just before the closing brace at the bottom of **AFloatingActor::Tick**:

		FVector NewLocation = GetActorLocation();
		float DeltaHeight = (FMath::Sin(RunningTime + DeltaTime) - FMath::Sin(RunningTime));
		NewLocation.Z += DeltaHeight * 20.0f;       //Scale our height by a factor of 20
		RunningTime += DeltaTime;
		SetActorLocation(NewLocation);

	[REGION:tip] The code we've just written will cause **FloatingActors** to bob up and down smoothly, using the _RunningTime_ variable we created to keep track of our movement over time. [/REGION] 

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		*	Now that we're done coding, we can compile by right-clicking our project in the **Solution Browser** and selecting the **Build** command, or by pressing the **Compile** button in the **Unreal Editor**. Once the compile succeeds, **Unreal Editor** will automatically load our changes.

			[![](CompileFromVS.png)](CompileFromVS.png)
	
			(compiling from **Visual Studio** pictured above)

			[![](CompileFromEditor.png)](CompileFromEditor.png)

			(compiling from the **Unreal Editor** pictured above)
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		[REGION:tip]
		When building in Xcode, you are only compiling the game project, not the Editor.
		[/REGION]
		
		*	Now that we're done coding, we can compile our project using XCode's Debug Configuration by clicking the **Product > Build** option.
		
			![](ProjectBuild_mac.png)
			
			(compiling using XCode's Debug Configuration pictured above)

		*	We can also compile using XCode's Development Configuration by clicking the **Product > Build For > Profiling** option.

			![](ProjectBuildProfile_mac.png)

			(compiling using XCode's Development Configuration pictured above)

			[![](CompileFromEditor.png)](CompileFromEditor.png)

			(compiling from the **Unreal Editor** pictured above)

		[REGION:note]
		When running the binary Editor, it is important to add the -game flag if you rebuilt your project in any **Uncooked** configuration, and the -debug flag if you rebuilt your project in any **Debug** configuration.
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----

We're now ready to create objects in **Unreal Editor** based on our code. For reference, all code used on this page is included below.

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		**FloatingActor.h**
			// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

			#pragma once

			#include "GameFramework/Actor.h"
			#include "FloatingActor.generated.h"

			UCLASS()
			class QUICKSTART_API AFloatingActor : public AActor
			{
				GENERATED_BODY()
	
			public:	
				// Sets default values for this actor's properties
				AFloatingActor();

				// Called when the game starts or when spawned
				virtual void BeginPlay() override;
	
				// Called every frame
				virtual void Tick( float DeltaSeconds ) override;
	
				float RunningTime;
			};

		**FloatingActor.cpp**
			// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

			#include "QuickStart.h"
			#include "FloatingActor.h"

			// Sets default values
			AFloatingActor::AFloatingActor()
			{
 				// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
				PrimaryActorTick.bCanEverTick = true;

			}

			// Called when the game starts or when spawned
			void AFloatingActor::BeginPlay()
			{
				Super::BeginPlay();
	
			}

			// Called every frame
			void AFloatingActor::Tick( float DeltaTime )
			{
				Super::Tick( DeltaTime );

				FVector NewLocation = GetActorLocation();
				float DeltaHeight = (FMath::Sin(RunningTime + DeltaTime) - FMath::Sin(RunningTime));
				NewLocation.Z += DeltaHeight * 20.0f;       //Scale our height by a factor of 20
				RunningTime += DeltaTime;
				SetActorLocation(NewLocation);
			}

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%Steps%