No, C# does not support preprocessor macros like C. Visual Studio on the other hand has snippets. Visual Studio’s snippets are a feature of the IDE and are expanded in the editor rather than replaced in the code on compilation by a preprocessor.
The #ifdef directive is used to check if a preprocessor symbol is defined. The standard (C11 6.4.2 Identifiers) mandates that identifiers must not start with a digit: The correct form for using the pre-processor to block out code is: You can also use: but you need to be confident that the symbols will not be inadvertently set by code … Read more
Those are called #include guards. Once the header is included, it checks if a unique value (in this case HEADERFILE_H) is defined. Then if it’s not defined, it defines it and continues to the rest of the page. When the code is included again, the first ifndef fails, resulting in a blank file. That prevents … Read more