To run the code, we must compile it because C# is a compiled language (at least in today’s world without an interactive read-eval-print-loop [REPL] loop C# tool). The act of compiling the code results in an assembly ready to be executed on the .NET runtime.
Open a command prompt window and change the directory to the place where you saved the Hello.cs file. As an aside, the use of .cs as the extension is not a requirement for the C# compiler; it’s just a best practice to store C# code files as such.
Because the search path doesn’t contain the .NET Framework installation folder, we have to enter the fully qualified path to the C# compiler, csc.exe. Recall that it lives under the framework version folder in %windir%\Microsoft.NET\Framework. ...