Question

Ok, so I keep getting a EXC_BAD_ACCESS error which I am guessing is alot like a seg fault error in C.

My book isn’t real specific on some of these details, so I need some help.

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSDateComponents *comps = [[NSDateComponents alloc ]init];
    [comps setYear:1984];
    [comps setMonth:7];
    [comps setDay:18];
    [comps setHour:0];
    [comps setMinute:0];
    [comps setSecond:0];

    NSCalendar *g =[[NSCalendar alloc ]init];
    NSDate *dateofbirth = [g dateFromComponents:comps];
    NSDate *now = [NSDate date];

    double timeSince = [now timeIntervalSinceDate:dateofbirth ];


    NSLog(@"your age %@", timeSince);



    [pool drain];



    return 0;
}

I think I am running into trouble because I am initializing and allocating memory within the pool. Is this correct?

Answer 1

The “%@” in your NSLog string expects an object, but you have passed in a double. Try:

    NSLog(@"your age %lf", timeSince);

Specifically, “%@” tries to call -message on the argument. Since your argument is a double, the runtime is ultimately trying to treat the double as a pointer, and dereference it (resulting in your EXC_BAD_ACCESS).

As far as memory management is concerned, you are leaking comps and g. At the end of the program, add a:

[comps release];
[g release];

Although this isn’t causing your error (nor is it really harming anything, as you are exiting and the OS is reclaiming the memory. As you learn Objective-C, however, not releasing your objects in other places will result in leaks)