Why tells the # sign to include for run

Question

Why
Is having

Answer 1

Here, read this to understand what it is:

http://www.cplusplus.com/doc/tutorial/preprocessor/

Answer 2

#
sign indicate..
That line must be compile by preprocessor ..
before compiler run .

Actually..
When we compile the program..
5 small program run..
that is.
1.pre processor
2 compiler
3 Assembler
4linker
5loder...

these small program run..
while we just give simple command to run