The C# language relies on types and methods in what the C# specification defines as a standard library for some of the features. The .NET platform delivers those types and methods in a number of packages. One example is exception processing. Every throw statement or expression is checked to ensure the object being thrown is derived from Exception. Similarly, every catch is checked to ensure that the type being caught is derived from Exception. Each version may add new requirements. To use the latest language features in older environments, you may need to install specific libraries. These dependencies are documented in the page for each specific version. You can learn more about the relationships between language and library for background on this dependency.
The compiler was originally written as an attempt to learn the C# language, it began as a tokenizer for the language, and then evolved into a parser for the language and later got the semantic analysis and code generation features in place. This explains the difference in coding styles from the tokenizer (which is the earliest code) and the code generation (which came at later phases).
This book includes topics like variables, math operations, looping, methods, and an in-depth look at the C# type system. In this reference book, you can explore some of the most useful advanced features of C# language.
C# has immense scope especially since its .NET version was made open source recently. Moreover, C# is quite easy to learn which contributes immensely to its popularity. Moreover, it has multiple features that allow the creation of durable system components. Some of these features are:
C++ has been around for a long time, which means there are lots of resources (many of them free) you could use to learn it. However, it has changed a great deal over the decades. You can see that in the answers here - people calling it insane and difficult are generally referring to features inherited from C or features that modern C++ developers rarely use, like manual memory management. You would probably find modern C++ quite easy to learn even with only PHP and CSS background. However, that won't help you if quants don't use modern C++. 59ce067264