When comparing The New Boston C Course vs SoloLearn, the Slant community recommends SoloLearn for most people. In the question“What are the best resources to learn C/C++?” SoloLearn is ranked 1st while The New Boston C Course is ranked 18th.
Specs
Question Ranking
Pros
Pro Video tutorials
Tutorials are presented as videos, making them easy to follow / see what's going on at each step. Many people find this format less daunting and easier to take in than traditional text based tutorials.
Pro Setup instructions included
The first video explains how to set up everything you need to get started on your machine. A lot of tutorials tell you about the language but leave you in the dark on how to get it up and running, creating a stumbling block before the first post.
Pro Suitable for beginners
No assumptions are made about prior knowledge, meaning anyone can start watching and pick up the basics of the language fairly quickly.
Pro Completely free
Pro Offline learning mode for mobile apps
Allows learning while disconnected from the net.
Pro Easy for beginners
Anyone can get started with this.
Pro Share and modify others' projects
Pro Browser-based code playgrounds
No software installation needed, just a modern web browser. On mobile devices though the mobile apps are highly recommended.
Pro Excellent mobile apps available
Pro Gamification
XP, levels, badges, certificates, etc.
Cons
Con Only the most commonly used languages are covered.
C++, Java, JavaScript, C#, Python, SQL, PHP, Swift, Ruby, JQuery, HTML, CSS. You won't find anything less common like Haskell, Erlang, Elixir, Common Lisp, Scheme, Clojure, Rust, etc.
Con Limited usefulness for intermediate or experienced programmers
No advanced coding challenges. Look for those on other sites like hackerrank.