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nightfire8199 wrote:I have followed Bran's Tutorial on osdever.net to the dot on the i's (figuratively). but when it comes time to compile, gcc (in Linux) has some UBER-problem with everything I do. the main compile error output (for main.c only) is that main() is not an int or something to that regard. and that puts is not correct. Below is the actual output:

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main.c:50: warning: return type of ‘main’ is not ‘int’
main.c: In function ‘main’:
main.c:63: warning: pointer targets in passing argument 1 of ‘puts’ differ in signedness

I'm not sure at all what this means, but I can tell that it isn't going to spit out a main.o, Help?

void main()

main()

int main()

nightfire8199 wrote:I'm not sure at all what this means, but I can tell that it isn't going to spit out a main.o, Help?

Candy wrote:

nightfire8199 wrote:I have followed Bran's Tutorial on osdever.net to the dot on the i's (figuratively). but when it comes time to compile, gcc (in Linux) has some UBER-problem with everything I do. the main compile error output (for main.c only) is that main() is not an int or something to that regard. and that puts is not correct. Below is the actual output:

Code: Select all

main.c:50: warning: return type of ‘main’ is not ‘int’
main.c: In function ‘main’:
main.c:63: warning: pointer targets in passing argument 1 of ‘puts’ differ in signedness

I'm not sure at all what this means, but I can tell that it isn't going to spit out a main.o, Help?

They mean that Bran hasn't been adhering to the C standard (at least, not the one you're trying to use to compile it). You're probably compiling it as C99, whereas it is written in C89 or older.

The first means that you have

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void main()

or

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main()

but the standard requires you to say

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int main()

because it will always have an integer return value.

The second means that you pass a parameter to puts that isn't of the right type, where the old compiler didn't complain (most likely since you could call undeclared functions). New compilers do complain because it's just plain wrong.

AJ wrote:but there's no need to quote the entire topic history in each answer

Craze Frog wrote:main() has a special meaning in C. Just rename your function k_main() or something and the warning will go away.

MessiahAndrw wrote:

Craze Frog wrote:main() has a special meaning in C. Just rename your function k_main() or something and the warning will go away.

No it doesn't. main() is no different to any other function. It is usually the first C/C++ function called in your code, but you can easily edit your assembly stub to change that.

MessiahAndrw wrote:

Craze Frog wrote:main() has a special meaning in C. Just rename your function k_main() or something and the warning will go away.

No it doesn't. main() is no different to any other function. It is usually the first C/C++ function called in your code, but you can easily edit your assembly stub to change that.

In implementation main() is no different...

int crudebox() {
    __asm__("#CODE START 2");
    __asm__("#CODE END 2");
    return 0;
}

int main() {
    __asm__("#CODE START");
    __asm__("#CODE END");
    return 0;
}

...
_crudebox:
	pushl	%ebp
	movl	%esp, %ebp
/APP
	#CODE START 2
	#CODE END 2
/NO_APP
	popl	%ebp
	xorl	%eax, %eax
	ret
...
_main:
	pushl	%ebp
	movl	$16, %eax
	movl	%esp, %ebp
	subl	$8, %esp
	andl	$-16, %esp
	call	__alloca
	call	___main
/APP
	#CODE START
	#CODE END
/NO_APP
	leave
	xorl	%eax, %eax
	ret

JamesM wrote:

MessiahAndrw wrote:

Craze Frog wrote:main() has a special meaning in C. Just rename your function k_main() or something and the warning will go away.

No it doesn't. main() is no different to any other function. It is usually the first C/C++ function called in your code, but you can easily edit your assembly stub to change that.

Not correct. In implementation main() is no different however it is defined to have a certain form by both the POSIX and C99 standards. Same with printf.

Won't cause an error but will cause warnings.