On Thu, Jan 14, 2010 at 6:08 PM, Rotary Engine <rotaryeng@earthlink.netwrote:
When I compile this extremely simple program I get this cryptic error:

"warning: passing argument 1 of ?printf? from incompatible pointer type"

Here is the program.

# include <stdio.h

int main()

{
printf(stdout, "this is a test\n");
}

What ever could be wrong? :)

Paul Lamar

It's a warning, not an error.  There is a difference.  Code that
generates compile warnings sometimes runs properly, depending on what
you want to do with it.

I believe in this case, stdout is extraneous..  stdout is the "file"
printf normally prints to.

Do a "man printf" in a shell terminal (linux, right).  I think you'll
see that the first argument of printf is const char..  fprintf (and
others) allow redirecting the output to other streams.

Most (maybe all) standard library c functions have man pages on unix hosts.


Regards,

Matt-


Also, if you really want to learn the guts of c programming, I
strongly recommend  K&R The C Programming Language..

http://en.wikipedia.org/wiki/The_C_Programming_Language_(book)

This is quite possibly the best written text book I have ever read.
It has concise examples for danged near anything you could want to do
with the c language.  It's not frilly, and it doesn't have large
chunks of example code, but all of the fundamental concepts are there
without any distracting garbage.


Matt-

Yes I have that one. I have 7 old books on C and one new one called
Essential Linux Device Drivers published in 2008. The Kernighan
and Ritchie  book was published in 1978.  I took a course in
C about 20 years ago so I am a bit rusty.

Thanks for the advice Matt.

Paul Lamar