Question

I have method overriding like below. Please ignore the way i written it may not be perfectly written, just for sample. But i want to know what would the output if i method overridden like this for variable “a”.

-> base class

@interface A 
{
    int a=15;
}
 -(int) myFunction;
@end

-> derived class

@interface B : A 
{
    int a=10;
}
 -(int) myFunction;
@end

Lets image “myFunction” returns “a”. Since, it does method overriding, when i call like,

B bObj; 
bObj.a = ? 

What should be the output 10 or 15 ?

Answer 1

I have assumed you are aware you can’t declare variables in a header like that and the initialisation there is just for simplicity.

Similarly, your B bObj hasn’t been initialised and isn’t a pointer

---

bObj.a would return 10. So would [bObj myFunction]. You have overridden the method and told the compiler to disregard previous implementations of this method and use the new one.

Can you suggest what the output of this might be:

A *obj = [[B alloc] init];
NSLog(@"%d", [obj myFunction]);

or this:

B *obj = [[A alloc] init];
NSLog(@"%d", [obj myFunction]);