Unreal Engine C++ Development — Complete Guide

In this tutorial, you'll learn about Unreal Engine C++ Development. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

Unreal Engine C++ development gives you full control over every aspect of your game — from custom gameplay mechanics to performance-critical subsystems — using the same C++ standards that power AAA titles like Fortnite and Hellblade 2. Unlike Blueprints, C++ offers superior performance, version control diffing, and access to the engine's entire API surface.

In this tutorial, you'll learn the Unreal reflection system (UObject, AActor, UActorComponent), UE5-specific header macros (UPROPERTY, UFUNCTION), memory management with smart pointers, and build a damage-able enemy class from scratch. By the end, you'll understand how C++ and Blueprints work together in a production pipeline.

Why Unreal C++ Matters

Blueprints handle 80% of gameplay logic in most UE5 projects, but the remaining 20% — AI queries, custom physics, network replication, large-scale data processing — requires C++. Unreal's reflection system makes C++ classes editable in the editor, so you get type safety at compile time and designer-friendly tweaking at runtime. At DodaTech, we use Unreal C++ for rendering optimization in Doda Browser's 3D map views.

Learning Path

flowchart LR
  A[Unreal Engine Guide] --> B[Unreal C++ Development
You are here]
  B --> C[Unreal Blueprints]
  B --> D[Game AI]
  style B fill:#f90,color:#fff

The UObject System

Every class in Unreal Engine inherits from UObject, which provides reflection, Garbage Collection, Serialization, and network replication. Create a custom class by inheriting from AActor (for world-placed objects) or UActorComponent (for attachable behavior).

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "DamageableEnemy.generated.h"

UCLASS()
class ADamageableEnemy : public AActor
{
    GENERATED_BODY()

public:
    ADamageableEnemy();

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Stats")
    float MaxHealth;

    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Stats")
    float CurrentHealth;

    UFUNCTION(BlueprintCallable, Category = "Combat")
    void TakeDamage(float DamageAmount);

    UFUNCTION(BlueprintImplementableEvent, Category = "Combat")
    void OnDeath();
};

Place this in Source/YourProject/Public/. The UPROPERTY macro exposes the variable to the editor and garbage collector. UFUNCTION(BlueprintCallable) makes it invocable from Blueprint graphs.

Implementing the Enemy Class

#include "DamageableEnemy.h"

ADamageableEnemy::ADamageableEnemy()
{
    PrimaryActorTick.bCanEverTick = false;
    MaxHealth = 100.0f;
    CurrentHealth = MaxHealth;
}

void ADamageableEnemy::TakeDamage(float DamageAmount)
{
    if (CurrentHealth <= 0.0f) return;

    CurrentHealth = FMath::Clamp(CurrentHealth - DamageAmount, 0.0f, MaxHealth);

    UE_LOG(LogTemp, Warning, TEXT("Enemy took %f damage. Health: %f"),
        DamageAmount, CurrentHealth);

    if (CurrentHealth <= 0.0f)
    {
        OnDeath();
        Destroy();
    }
}

The FMath::Clamp prevents negative health values. After the enemy dies, OnDeath() is called — because it's BlueprintImplementableEvent, designers can define the death animation, particle effect, or loot drop entirely in Blueprints.

Expected log output:

LogTemp: Warning: Enemy took 25.000000 damage. Health: 75.000000
LogTemp: Warning: Enemy took 30.000000 damage. Health: 45.000000
LogTemp: Warning: Enemy took 50.000000 damage. Health: 0.000000

Components and Ownership

Unreal encourages Composition Over Inheritance. Attach components to actors to build complex behavior from reusable pieces.

#include "Components/SphereComponent.h"
#include "Particles/ParticleSystemComponent.h"

void ADamageableEnemy::PostInitializeComponents()
{
    Super::PostInitializeComponents();

    USphereComponent* CollisionComp = CreateDefaultSubobject<USphereComponent>(TEXT("CollisionComp"));
    CollisionComp->InitSphereRadius(50.0f);
    CollisionComp->SetCollisionProfileName(TEXT("Pawn"));
    RootComponent = CollisionComp;

    UParticleSystemComponent* DeathEffect = CreateDefaultSubobject<UParticleSystemComponent>(TEXT("DeathEffect"));
    DeathEffect->SetupAttachment(RootComponent);
    DeathEffect->SetAutoActivate(false);
}

CreateDefaultSubobject registers the component for lifetime management and editor visibility. The collision sphere becomes the root, and the particle system is attached to it but only activates when OnDeath() triggers it.

Practice Questions

1. What does the GENERATED_BODY() macro do in a UCLASS declaration?
2. Why would you use UFUNCTION(BlueprintImplementableEvent) instead of BlueprintCallable?
3. How does Unreal's garbage collector know which objects to keep alive?

Frequently Asked Questions

What is the difference between EditAnywhere and EditDefaultsOnly?

EditAnywhere allows the value to be changed per-instance in the editor. EditDefaultsOnly only allows changes to the class defaults (blueprint default object), not individual placed actors.

Do I need to manually delete UObjects in Unreal C++?

No. Unreal's garbage collector uses reference counting through UPROPERTY() macros. Objects without any UPROPERTY() pointer referencing them are collected on the next GC cycle. Use TSharedPtr and TUniquePtr for non-UObject memory.

How do C++ classes communicate with Blueprints?

Through UPROPERTY(BlueprintReadWrite), UFUNCTION(BlueprintCallable), UFUNCTION(BlueprintImplementableEvent), and UFUNCTION(BlueprintNativeEvent). The latter lets C++ provide a default implementation that Blueprint can override.

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