Re: Where does C++ fit in?

"Hello world" is probably not the best test of a compiler, since were mostly using libraries, but I'll bite.

I compile the following program natively using GCC 3.2.2 under Redhat Linux.

main.c:

#include

int main(int argc,char* argv[]){ printf("Hello world.\n"); }

% gcc -fno-exceptions -fno-rtti -o main -x c main.c % strip main

-rwxrwxrwx 1 mike mike 2788 Apr 30 17:28 main

% gcc -fno-exceptions -fno-rtti -o main -x c main.c % strip main

-rwxrwxrwx 1 mike mike 2792 Apr 30 17:27 main

The C++ program is 4 bytes larger.

BTW, I got the same results with exceptions and rtti enabled.

While we're at it, here is the result of a few other GCC cross compilers.

xscale-elf-gcc -fno-exceptions -fno-rtti -c -x c main.c xscale-elf-strip main.o

-rw-rw-rw- 1 mike mike 500 Apr 30 17:49 main.o

xscale-elf-gcc -fno-exceptions -fno-rtti -c -x c++ main.c xscale-elf-strip main.o

-rw-rw-rw- 1 mike mike 508 Apr 30 17:50 main.o

powerpc-eabi-gcc -fno-exceptions -fno-rtti -c -x c main.c powerpc-eabi-strip main.o

-rw-rw-rw- 1 mike mike 532 Apr 30 17:52 main.o

powerpc-eabi-gcc -fno-exceptions -fno-rtti -c -x c++ main.c powerpc-eabi-strip main.o

-rw-rw-rw- 1 mike mike 536 Apr 30 17:51 main.o

h8300-elf-gcc -fno-exceptions -fno-rtti -c -x c main.c h8300-elf-strip main.o

-rw-rw-rw- 1 mike mike 428 Apr 30 17:54 main.o

h8300-elf-gcc -fno-exceptions -fno-rtti -c -x c++ main.c h8300-elf-strip main.o

-rw-rw-rw- 1 mike mike 428 Apr 30 17:54 main.o

Again, this is a bad and quite way to compare languages, but ...

To paraphrase someone whose name escapes me, "First make it right, then optimize."

OK (frantic shuffling of goalposts) now compare with the --static switch :)

Only 100 more bytes in C++, but virtually all of that is from the startup code it is linked to. When compiling to an assembly I can see that the C++ version has merely one extra move instruction so that main() returns a valid value.

Jon Bentley. author of _Programming Pearls_

- a book no embedded software developer should be without.

-- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at

~ ; cat hello.c #include int main(void) { return printf("Hello world\n"); } ~ ; ln hello.c hello.cc ~ ; gcc hello.c ~ ; ls -l a.out

-rwxrwxr-x 1 pete pete 11251 May 1 00:16 a.out ~ ; g++ hello.cc ~ ; ls -l a.out

-rwxrwxr-x 1 pete pete 11356 May 1 00:16 a.out ~ ;

Hmmm. 1% difference? ;)

(A hello world using streams in C++ comes to 12.9k. You're right. This is highly non-scientific ;))

pete

Oh dear. ;)

~ ; gcc --static hello.c ~ ; ls -l a.out

-rwxrwxr-x 1 pete pete 1692714 May 1 00:21 a.out ~ ; strip a.out ~ ; ls -l a.out

-rwxrwxr-x 1 pete pete 385632 May 1 00:21 a.out

~ ; g++ --static hello.cc ~ ; ls -l a.out

-rwxrwxr-x 1 pete pete 1692715 May 1 00:21 a.out ~ ; strip a.out ~ ; ls -l a.out

-rwxrwxr-x 1 pete pete 385632 May 1 00:22 a.out

;)

pete

s/embedded//

Along with Kernighan & Pike's "The Practice of Programming", Brooks' "The Mythical Man Month", and Bignell and Fortune's "Understanding Systems Failures".

pete

gcc -static -fno-exceptions -fno-rtti -x c++ -o main main.c strip main ls -l main

-rwxrwxrwx 1 mike mike 377888 May 1 07:53 main

gcc -static -fno-exceptions -fno-rtti -x c -o main main.c strip main ls -l main

-rwxrwxrwx 1 mike mike 377888 May 1 07:54 main

You forgot the -fno-exceptions -fno-rtti switches. My results have identical sizes with those.

gcc -static -fno-exceptions -fno-rtti -x c -o main main.c strip main ls -l main

-rwxrwxrwx 1 mike mike 377888 May 1 07:54 main

gcc --static -fno-exceptions -fno-rtti -x c++ -o main main.c strip main ls -l main

-rwxrwxrwx 1 mike mike 377888 May 1 07:56 main