How do I compile Objective-C code with GCC?
When I try to compile this code, I got the form here with gcc:
#import <stdio.h>
#import <objc/Object.h>
@interface Hello: Object
- (void) init;
- (void) say;
@end
@implementation Hello
- (void) init {
[super init];
}
- (void) say {
printf("Hello, world!\n");
}
@end
int main() {
Hello *hello = [Hello new];
[hello say];
[hello free];
return 0;
}
with code line: g ++ -x objective-c ++ test.mm -otest -lobjc
I get the following warnings when compiling:
test.mm:11:14: warning: ‘Object’ may not respond to ‘-init’ [enabled by default]
test.mm:11:14: warning: (Messages without a matching method signature
[enabled by default]
test.mm:11:14: warning: will be assumed to return ‘id’ and accept
[enabled by default]
test.mm:11:14: warning: ‘...’ as arguments.) [enabled by default]
test.mm: In function ‘int main()’:
test.mm:19:28: warning: ‘Hello’ may not respond to ‘+new’ [enabled by default]
test.mm:21:14: warning: ‘Hello’ may not respond to ‘-free’ [enabled by default]
and if i try to run - i get SIGSEGV:
$> ./test
$> Segmentation fault
What am I doing wrong?
env: linux-x86_64, gcc-4.7.2
Thank.
source to share
This code is incorrect. And ancient. It would never work. Now it will have (corrected and added some additional examples).
First check if GNUStep is installed. If you do, switch to using NSObject and libFoundation (actually libgnustep-base
, as Fred points out in the comments).
Secondly, [IIRC - Scratched Old Brain Cells] that init
were still returned (id) when Object was still the root class. Since you are not doing anything useful with this method init
, just remove it entirely.
Compiler errors indicate that your subclass is Hello
not properly inheriting from Object
, which makes no sense.
source to share