printf warning

[Perry Smith]

Hi,

I'm trying to help a guy using Python.  From Python on a PPC Mac, he  
is trying to call printf
in the standard C shared library with a format string, an int, and  
some doubles.  I'm thinking
that the calling sequence from python back into the real C code is  
not going to call printf
properly because, as I recall, to call printf properly, the compiler  
must see the prototype so
it knows to actually push the arguments and not pass them in  
registers.  So, I tried to
demonstrate this to him by writing the following program:

int main()
{
     printf("int=%d double=%f\n", 5, 8.2);
     return 0;
}

(note, I'm not including anything.) When I compile it I get this:

make -k dog && ./dog
cc     dog.c   -o dog
dog.c: In function 'main':
dog.c:3: warning: incompatible implicit declaration of built-in  
function 'printf'
int=5 double=8.200000

So, somehow, gcc "knows" about printf (I guess that is what the  
warning is
telling me).  Can I tell gcc to "forget" and go ahead and produce  
whatever
code its best guess is.

Or... can someone confirm that to call functions that takes a  
variable number
of mixed arguments, the compiler has to see a prototype in order to  
produce
working code.

Perry Smith ( pedz@easesoftware.com )
Ease Software, Inc. ( http://www.easesoftware.com )

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