Question

Consider the following Objective-C code:

@interface ClassA : NSObject {

}
-(void) printVal;
@end


@implementation ClassA
-(void) printVal {
    int val;
    NSLog(@"%i", val);
}
@end


int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    ClassA* cA = [[ClassA alloc] init];
    [cA printVal];
    [cA printVal];
    [cA printVal];

    [pool drain];
    return 0;
}

Why is this output:

2012-11-29 22:12:06.586 TestOne[20266:903] 0
2012-11-29 22:12:06.587 TestOne[20266:903] 32767
2012-11-29 22:12:06.588 TestOne[20266:903] 32767

In other words, why is val not reinitialized to 0 when it is redeclared, and why does it receive the value 32767 every subsequent time the method is called?

Answer 1

That is garbage value.

Initialise it with some value.

EDIT:

Storage class specifiers has some default value as

for auto- garbage value.

for static- 0.

for global/extern- 0;

for register-garbage.

In your case it is auto.

OHHH!!! I fotgot to answer your second part 🙁

Why initially it came as 0 and later on some 32767.

And you rightly pointed out in that link, now no need to explain in this answer. What can i do is refer to that link only.

How does an uninitiliazed variable get a garbage value?