C++ Change StaticMeshComponent of AStaticMeshActor

I am trying to change every Static Mesh Actor’s Material property.
I know I need to iterate over each Actor and find Static Mesh Component.
However, I can not modify Material properly.

Here is my code,

GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, TEXT("START Modeling()"));

//Find Actor and change Material
UWorld* world = GetWorld();

//Material Path
FString matPath = "Material'/Game/StarterContent/Materials/M_Metal_Gold.M_Metal_Gold'";
//Material Instance
UMaterialInstanceConstant* material = Cast<UMaterialInstanceConstant>(StaticLoadObject(UMaterialInstanceConstant::StaticClass(), nullptr, *(matPath)));
//Iterate Every Static Mesh Actor
for (TActorIterator<AStaticMeshActor> ActorItr(world); ActorItr; ++ActorItr)
	AStaticMeshActor *Mesh = *ActorItr;
    //Just for Degbuging Purpose
	GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("Actor: %s"), *(ActorItr->GetName())));
	GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("Location: %s"), *(ActorItr->GetActorLocation().ToString())));
    //Get Static Mesh Component
	TArray<UStaticMeshComponent*> MaterialComps;
    //I get this code from community answer. I do not know how it works.
	for (int32 Index = 0; Index != MaterialComps.Num(); ++Index)
		UStaticMeshComponent* targetComp = MaterialComps[Index];
		int32 mCnt = targetComp->GetNumMaterials();
		for (int i = 0; i < mCnt; i++)
                    //This is the core code which actually changing material.
			targetComp->SetMaterial(0, material);




I think your problem is in the line


Why not just

for (AStaticMeshActor* actor : actorArray)
    int matNum = actor->GetStaticMeshComponent()->GetNumMaterials();
    for (int i = 0; i < matNum; i++) 
        actor->GetStaticMeshComponent()->SetMaterial(i, yourMaterial);