[OC]:unrecognized selector sent to instance 0x7f9521c13d10

#import<Foundation/Foundation.h>

@interface Stu : NSObject
{

}

@end

@implementation Stu

@end

int main()
{
Stu *s = [Stu new];
[s hello];
return 0;
}

由上面程序而产生的error:unrecognized selector sent to instance 0x7f9521c13d10是说：给对象发送一条不能被识别的消息hello，这个问题使得程序能链接不能编译