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Dear All,

Could you please tell me what is a "#" stand for in c++?

Why there is "#if 1" in program description?

It go with "#endif"

Could you please explain it? thank you very much.

Best regards,
Boki.

boki wrote:
> Dear All,
>
> Could you please tell me what is a "#" stand for in c++?
>
The "#" indicates a preprocessor directive. Your favorite C/C++ book
will tell you more.

BR,
Peter

In article <9ag1d.47114$>,
Peter Kragh <_> wrote:
>boki wrote:
>>
>> Could you please tell me what is a "#" stand for in c++?
>
>The "#" indicates a preprocessor directive. Your favorite C/C++ book
>will tell you more.

Or a Google search:

<http://www.google.com/search?q=C%2B%2B+%22preprocessor+directives%22>

--
Jon Bell <> Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA

boki wrote:

> Dear All,
>
> Could you please tell me what is a "#" stand for in c++?
The '#' character is an indicator that a preprocessor
keyword is coming up.


> Why there is "#if 1" in program description?
>
> It go with "#endif"
The #if..#endif sequence allows the preprocessor to
remove blocks of source code before it is passed to
the compiler. Thus it can behave as an easy way
to "comment-out" blocks of code.

Many programmers use:
#if 0
/* code not compiled */
#endif
To comment out the code. If the programmer wants
the code to be compiled, the '0' is changed to
a '1':
#if 1
/* code is now compiled */
#endif

>
> Could you please explain it? thank you very much.
>
> Best regards,
> Boki.
Read up on preprocessor directives.


--
Thomas Matthews

C++ newsgroup welcome message:
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Other sites:
http://www.josuttis.com -- C++ STL Library book

Thomas Matthews <> wrote in message news:<lIg1d.1388$ m>...
> boki wrote:
>
> > Dear All,
> >
> > Could you please tell me what is a "#" stand for in c++?
> The '#' character is an indicator that a preprocessor
> keyword is coming up.

May be coming up: # by itself is a valid directive (which has
no effect).

Thank you all very much.

Best regards,
Boki.

Thomas Matthews <> wrote in message news:<lIg1d.1388$ m>...
> boki wrote:
>
> > Dear All,
> >
> > Could you please tell me what is a "#" stand for in c++?
> The '#' character is an indicator that a preprocessor
> keyword is coming up.
>
>
> > Why there is "#if 1" in program description?
> >
> > It go with "#endif"
> The #if..#endif sequence allows the preprocessor to
> remove blocks of source code before it is passed to
> the compiler. Thus it can behave as an easy way
> to "comment-out" blocks of code.
>
> Many programmers use:
> #if 0
> /* code not compiled */
> #endif
> To comment out the code. If the programmer wants
> the code to be compiled, the '0' is changed to
> a '1':
> #if 1
> /* code is now compiled */
> #endif
>
> >
> > Could you please explain it? thank you very much.
> >
> > Best regards,
> > Boki.
> Read up on preprocessor directives.
>
>
> --
> Thomas Matthews
>
> C++ newsgroup welcome message:
> http://www.slack.net/~shiva/welcome.txt
> C++ Faq: http://www.parashift.com/c++-faq-lite
> C Faq: http://www.eskimo.com/~scs/c-faq/top.html
> alt.comp.lang.learn.c-c++ faq:
> http://www.comeaucomputing.com/learn/faq/
> Other sites:
> http://www.josuttis.com -- C++ STL Library book

Thomas Matthews wrote:

> boki wrote:
>
> > Dear All,
> >
> > Could you please tell me what is a "#" stand for in c++?
> The '#' character is an indicator that a preprocessor
> keyword is coming up.
>
> > Why there is "#if 1" in program description?
> >
> > It go with "#endif"
> The #if..#endif sequence allows the preprocessor to
> remove blocks of source code before it is passed to
> the compiler. Thus it can behave as an easy way
> to "comment-out" blocks of code.
>
> Many programmers use:
> #if 0
> /* code not compiled */
> #endif
> To comment out the code. If the programmer wants
> the code to be compiled, the '0' is changed to
> a '1':
> #if 1
> /* code is now compiled */
> #endif

the example you give is like a comment, however #if can also be used to
selectively add different options into the code at compile time. For
example:

#if defined(DEBUG)
#define MYERROR(x) printf("x")
#else
#define MYERROR(x)
#endif

which allows you to compile printf statements in your program for
debugging then easily take them out when you are done debugging, simply
by commenting out the line that defines DEBUG

David