UE4_GetAllFilesInDirectory.cpp

TArray<FString> GetAllFilesInDirectory(const FString directory, const bool fullPath, const bool withoutExtention, const FString onlyFilesStartingWith, const FString onlyFilesWithExtension)
{
	// Get all files in directory
	TArray<FString> directoriesToSkip;
	IPlatformFile& PlatformFile = FPlatformFileManager::Get().GetPlatformFile();
	FLocalTimestampDirectoryVisitor Visitor(PlatformFile, directoriesToSkip, directoriesToSkip, false);
	PlatformFile.IterateDirectory(*directory, Visitor);
	TArray<FString> files;
	for (TMap<FString, FDateTime>::TIterator TimestampIt(Visitor.FileTimes); TimestampIt; ++TimestampIt)
	{
		const FString filePath = TimestampIt.Key();
		const FString fileName = FPaths::GetCleanFilename(filePath);
		bool shouldAddFile = true;
		// Check if filename starts with required characters
		if (!onlyFilesStartingWith.IsEmpty())
		{
			const FString left = fileName.Left(onlyFilesStartingWith.Len());
			if (!(fileName.Left(onlyFilesStartingWith.Len()).Equals(onlyFilesStartingWith)))
				shouldAddFile = false;
		}
		// Check if file extension is required characters
		if (!onlyFilesWithExtension.IsEmpty())
		{
			if (!(FPaths::GetExtension(fileName, false).Equals(onlyFilesWithExtension, ESearchCase::IgnoreCase)))
				shouldAddFile = false;
		}
		// Add full path to results
		if (shouldAddFile)
		{
			if (withoutExtention)
				files.Add(fullPath ? filePath : FPaths::GetBaseFilename(filePath));
			else
				files.Add(fullPath ? filePath : FPaths::GetCleanFilename(filePath));
		}
	}
	return files;
}