difference between nil and NULL [duplicate]

Question

Possible Duplicate:
NULL vs nil in Objective-C
Objective-C: What's the difference between NULL, nil and @“”?

all I have a simple problem that my objective variable has NULL value in it. and it simply enter in the if condition. I have to check that if variable objective length is greater then zero and no null value then enter in condition.

and When I use NULL or nil in comparison?

THANKS

Answer 1

They are the same. However, it is conventional to use nil to compare against an objc object, and when assigning to an objc object.

Answer 2

Assuming we're talking about Objective-C:

nil (all lower-case) is a null pointer to an Objective-C object.

Nil (capitalized) is a null pointer to an Objective-C class.

NULL (all caps) is a null pointer to anything else.

Answer 3

In this case it seems that you have a string with a value of "(null)". This can happen when you attempt to append or format content into the string that was null itself. It's a valid string that is not NULL or nil and is 8 characters long. So it enters your loop.

In objective-c, NULL and nil are the same thing (the number 0). But the style guide will tell you to use NULL for pointers and nil for classes derived from NSObject.