Have you read any books on Unreal Engine 4 and C++? If so, which ones were good? Thanks!

Unreal Engine 4 is a crafty and complicated game engine I have ever used, previously a Unity developer, the problem with UE4 is not the programming or development it's the community. Unity was released earlier before UE4 and before that UE4 was only monthly payment so the community tends to lagged behind and development is highly closed off and the marketplace is lacking, but it's growing at slow incremental rate.

My advice as I am doing now is learn the BASIC from taking a small courses on Udemy, Unreal Engine C++ Developer By Ben Tristrem, then simply acquiring the following books I listed:
 

1. C++ Primer Fifth Edition By Stanley B. Lippman

2. Code Complete Second Edition By Steve McConnell

Focus on the basic parts of your game to get good and gain experience while enhancing your skills with Unreal Engine 4 as their syntax are very complicated and you need the full understanding of the C++ language. Mostly my projects consists of mixture of Blueprint and C++ to hasten my development which I do not recommend to rely heavily on both or one of each.

There are free tutorials on YouTube on UE4 Blueprint, some developers are sharing their experience on that site, and the official UnrealEngine.com community. So, you can always try those route to gain experience, there are books for Blueprint but I do not highly recommend getting those as EpicGames tend to update and upgrade Unreal Engine 4 faster so what you've learned from a book will not follow through in the next update or upgrade of the engine. I still highly recommend for developers to take Ben Tristrem's Udemy tutorial and participate in his Facebook and Twitter group, be part of the UE4 community discussions, and gaining more experience in the C++ programming language less on the Blueprint because it gets outdated.