How to do it...

1. In your code, enter a line of code using the following form:

UE_LOG(LogTemp, Warning, TEXT("Some warning message") );

For instance, if you wanted to add this to the script in the previous recipe, it may look like this:

#include "Chapter_01GameModeBase.h"

void AChapter_01GameModeBase::BeginPlay()
{
  Super::BeginPlay();

  // Basic UE_LOG message
  UE_LOG(LogTemp, Warning, TEXT("Some warning message") );
}

2. Turn on the Output Log inside the UE4 editor by going to Window | Developer Tools | Output Log to see your log messages printed in that window as your program is running:

3. If you play your game by clicking on the Play button from the top toolbar, you should notice our text being displayed in yellow on the log:

To make your output easier to see, you can clear the Output Log at any time by right-clicking on it within the window and selecting Clear Log.