Indentation of preprocessing directives

[Dave]

Hello all,

In standard C++, is it required that preprocessing directives (#include,
#if, etc...) start in column 0, or is that just a C thing?

Thank,
Dave

 

[Phlip]

In standard C++, is it required that preprocessing directives (#include,
#if, etc...) start in column 0, or is that just a C thing?

Obsolete Cs required column 0, I think. But the modern standards are
probably "first non-blank character is a # in a line".

Curiously, blanks may occur between the # and the following directive. So to
indent nested directives you could do this...

#ifndef db

# ifndef _DEBUG
# error don't use this in release mode
# endif

# include <sstream>
# include <iostream>
# include <string>

....or this:

#ifndef db

#ifndef _DEBUG
#error don't use this in release mode
#endif

#include <sstream>
#include <iostream>
#include <string>

 

[Jack Klein]

Hello all,

In standard C++, is it required that preprocessing directives (#include,
#if, etc...) start in column 0, or is that just a C thing?

Thank,
Dave

Not a C or C++ thing, not since the original 1989 ANSI C standard.

--
Jack Klein
Home: http://JK-Technology.Com
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