Shermans's Notes
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Unreal - Logging


Logging to Game Window


General logging Macro with configurable category and verbosity.

  • UE_LOG(LogTemp, Warning, TEXT("We %s hit %s"), *actor_name, *our_name);
    • LogTemp and Warning are the Category and Verbosity Mask. See engine source Engine\Source\Runtime\Core\Public\Logging\LogVerbosity.h for listings
    • The text portion can use printf specifiers
    • when passing FString, remember to dereference them so the log can use the underlaying TCHAR,
  • Verbosity levels :

CustomLog Categories

  • In the header: DECLARE_LOG_CATEGORY_EXTERN(LogCatName, DefaultVerbosity, CompileTimeVerbosity)

  • in the implimentation file DEFINE_LOG_CATEGORY(LogCatName)

  • You should also be able to define these in blunk in a common header, in order to use a more common category without including unrelated files.

Logging Of Data Types


  • Returns an FString, so when logging make sure to dereference!
    • UE_LOG(LogCat, LogType, TEXT("This is enum %s"), *UEnum::GetValueAsName(value).ToString())



Logging macros that export data to the ue-visual-logger allow collection and display of debug data over time.

Logs in Shipping Build

It can be useful the see logs in a shipping build but not in game as the build process is different and can quite often have changes that do not happen in editor.

To enable output logs in shipping:

  • Add the following to your modules build target:
// enable logs and debugging for Shipping builds  
if (Configuration \== UnrealTargetConfiguration.Shipping)  
 BuildEnvironment \= TargetBuildEnvironment.Unique;  
 bUseChecksInShipping \= true;  
 bUseLoggingInShipping \= true;  
  • Run the build exe with -Log as an argument
    • Build.exe -Log