Sanjeev Gopinath <sanjeevsinc...@...> wrote:
>
> Hello all,
> I've some series of questions...!
> * Is there any difference when a C program runs in a C++
> compiler?
There's no such thing as a C program to a C++ compiler.
The following is a C program. Tell me which language your
C++ compiler thinks it is...
#include <stdio.h>
char foobar;
int main()
{
struct foobar { char a[2]; };
if (sizeof(foobar) == sizeof(struct foobar))
puts("C++ compiler.");
else
puts("C compiler.");
}
> (I mean the approaches taken internally by the C++ compiler)
A C++ compiler will, by definition compile C++ programs, whatever
the source code author's notion of which language it was written
in.
These days, C and C++ compilers tend to be bundled together.
Modern compilers (e.g. GNU) will actually translate the source
language into an intermediate language anyway, thus using the
same optimisors and assemblers for both.
But there have been systems where C++ calling conventions are
different to C calling conventions. There are also subtle
differences in the languages which mean that a C++ compiler
must treat the same line of code differently to a C compiler.
> * Will the C++ compiler understand it as a C program?
No more than a COBOL or FORTRAN compiler will understand it
as a C program.
> If so, how does it differentiate?
It doesn't. Some command line 'compilers' are really wrappers,
detecting the file extension and passing the source to the
appropriate 'real' compiler. The real compilers however
generally only understand one language.
> * Will there be any storage difference between a C and C++
> compiler?
Storage difference?
C++ implementations tend to be much larger than C ones because
the language is considerably more complex, and C++ has a much
larger standard library.
--
Peter
