Header file inclusion

Lets say that I have a header file a.hxx which includes b.hxx and c.hxx.

Now if I cinlude this a.hxx file in the d.cxx file, does b.hxx and c.hxx automatically (implicitly) get included?

P.S: This is not a homework question. I was cur开发者_开发技巧ious to know about this.

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Yes it does. When you use d.hxx file it has all the contents of a.hxx b.hxx and c.hxx

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Yes, the whole thing gets treated as one big stream of characters:

pax$ cat a.hxx
#warning START A
#include "b.hxx"
#include "c.hxx"
#warning END.. A
//==============

pax$ cat b.hxx
#warning START B
#warning END.. B
//==============

pax$ cat c.hxx
#warning START C
#warning END.. C
//==============

pax$ cat d.cxx
#warning START D
#include "a.hxx"
#warning END.. D
//==============

 

pax$ gcc -c -o d.o d.cxx
d.cxx:1:2: warning: #warning START D
In file included from d.cxx:2:
a.hxx:1:2: warning: #warning START A
In file included from a.hxx:2,
                 from d.cxx:2:
b.hxx:1:2: warning: #warning START B
b.hxx:2:2: warning: #warning END.. B
In file included from a.hxx:3,
                 from d.cxx:2:
c.hxx:1:2: warning: #warning START C
c.hxx:2:2: warning: #warning END.. C
In file included from d.cxx:2:
a.hxx:4:2: warning: #warning END.. A
d.cxx:3:2: warning: #warning END.. D