Proprocessor Directives

Question 1

The preprocessor directives give instruction to the compiler to preprocess the information before actual compilation starts.

All preprocessor directives begin with #, and only white-space characters may appear before a preprocessor directive on a line. Preprocessor directives are not statements, so they do not end with a semicolon (;).

C# compiler does not have a separate preprocessor; however, the directives are processed as if there was one. In C# the preprocessor directives are used to help in conditional compilation. Unlike C and C++ directives, they are not used to create macros. A preprocessor directive must be the only instruction on a line.

Answer 1

1	
#define

It defines a sequence of characters, called symbol.

2	
#undef

It allows you to undefine a symbol.

3	
#if

It allows testing a symbol or symbols to see if they evaluate to true.

4	
#else

It allows to create a compound conditional directive, along with #if.

5	
#elif

It allows creating a compound conditional directive.

6	
#endif

Specifies the end of a conditional directive.

7	
#line

It lets you modify the compiler’s line number and (optionally) the file name output for errors and warnings.

8	
#error

It allows generating an error from a specific location in your code.

9	
#warning

It allows generating a level one warning from a specific location in your code.

10	
#region

It lets you specify a block of code that you can expand or collapse when using the outlining feature of the Visual Studio Code Editor.

11	
#endregion

It marks the end of a #region block.