Compiler Error

The declaration for main should be

int main(void)

Frank Caggiano has given you the answer.

More details...

If that "KR" reference is to K&R, that's a reference to K&R C, which is C code that predates the ANSI and ISO C standards. That's very old C code. K&R C code will usually generate warnings and errors, as compilers have become much better at detecting errors and much more strict in the twenty+ years since K&R C was the current standard.

In C, warnings are coding errors that may well lead the program astray; best to address and fix those as found. (With clang, the -Weverything switch turns on all of the warnings. That's found more than a few latent bugs in C code, and particularly in K&R C code...)

main has returned a value ab=nd has been required to be type for quite some time, I'm surprised you are just seeing the warning now.

In any case the correct way to write that funtion wourl be

int main(void)

{

…code

return 0;

}

Main is ust a function like any other and should return a value. In its case the value returned indicates the success of failure of the program.

K&R is fine, still refer to it myself from time to time. But as Mr. Hoffman wrote a lot has changed since it was written and even if you are learnign from it or using it for reference you need to update the parts that are out-of-date.

regards

Message was edited by: Frank Caggiano - of course of you are writing on a Mac you really should make use of Xcode, you are missing a lot if you do not take the time to learn it. Apple has created a very good IDE.

danuke wrote:

To be honest, I don't know why, but I just like the K&R book for some reason. I know that I will have to grab hold of something newer one of these days. But then again, I still like Text adventure games the best. ;^)

I'd suggest acquiring the second edition of the Kernigan and Richie book, if you're fond of the original K&R book. That's updated for the ANSI/ISO C C89/C90 standards.

The more recent C99 and C11 standards are not covered in that book. But at least the code from the K&R second edition will generally still compile with current-generation compilers, unlike the pre-ANSI code from the first edition.

Here's some code that compiles cleanly, and runs correctly.

#include <stdio.h>

/* print Fahrenheit-Celsius table

for fahr = 0, 20, ..., 300 */

int main(void)

{

int fahr, celsius;

int lower, upper, step;

lower = 0; /* lower limit of temperature table */

upper = 300; /* upper limit */

step = 20; /* step size */

fahr = lower;

printf("Fahr\tCel\n");

while (fahr <= upper) { /* While loop */

celsius = 5 * (fahr-32) / 9;

printf("%d\t%d\n", fahr, celsius);

fahr = fahr + step;

}

exit( EXIT_SUCCESS );

}

I used an exit() in the above example, but you can also return off the end of main().

If you code K&R, you'll be chasing various of these changes around.

Yes, I'd (also) suggest use Xcode, and would create a command-line project here, and then build and test and run your code within that IDE. Xcode is a very good IDE for writing C.

FWIW, there are more developers over in the Apple developer forums, as well.

right everything just links to clang now on OS X.

If you want to be blown away, install and launch Xcode and create a new command-line tool project.

Xcode C syntax highlighting and live diagnostics are all quite impressive, and very useful. As a long-time command-line compiler user (and one that still uses the command line heavily), Xcode is very powerful, and a very effective tool or C development.

The switch from gcc to clang meant that the compiler diagnostics, code analysis, code correction suggestions and the rest could all be directly tied directly into Xcode, too. As you enter the source code in the editor, the compiler will be run and will spot errors as you enter them, suggest corrections, and the source code completion will suggest symbols directly from your source code.

I'm moving more and more of my command line development over into Xcode, as it's easier and faster — even if I later come back to the command line and create a script for a non-Xcode build or other such tasks.

This before even getting to the available frameworks, which are massively more advanced than what is available in standard C. (The command line template in Xcode will set you up to use the frameworks from a command line program, so you can either learn more about those as you go, or — at least for now — just delete out the template code that you don't need for your work. Or create or find and install an ANSI/ISO template for Xcode if you wanted to get fancy, but I've not bothered with that.)

danuke wrote:

I just noticed that man cc brings up the page for clang. I suppose that its the default now??

man gcc shows nothing

GCC is gone. They had finally pushed the free software politics past the breaking point.