Why do many GIS job advertisements require proficiency in C#, while few require C++? What is the difference between them?

Because. net architecture has become the mainstream at present, adopting C# has the advantages of simple interface, small code and easy maintenance, and the disadvantages of C++ in interface design and human-computer interaction have become increasingly obvious. Its advantages lie in byte-level data processing and real-time communication, so I suggest you switch to C#. I am also a C++ programmer, and it has only been a week since I switched to C#. I hope I can help you. Thank you.