What is meant by nil in Objective-C?

Objective-C builds on C’s representation of nothing by adding nil . nil is an object pointer to nothing. Although semantically distinct from NULL , they are technically equivalent. But in Objective-C, invoking a method on nil returns a zero value — which is to say, “ nil begets nil “. …

What are null pointers in C?

A Null Pointer is a pointer that does not point to any memory location. It stores the base address of the segment. The null pointer basically stores the Null value while void is the type of the pointer. A null pointer is a special reserved value which is defined in a stddef header file.

What is meant by null pointer?

A null pointer is a pointer which points nothing. a) To initialize a pointer variable when that pointer variable isn’t assigned any valid memory address yet. b) To pass a null pointer to a function argument when we don’t want to pass any valid memory address.

Is nil and null the same?

Nil is used to represent a null pointer to an Objective-C class. NULL is used to represent a null pointer to anything else. All these, happen to have the numeric value of 0. They’re all zero, but “NULL” is a void *, “nil” is an id, and “Nil” is a Class pointer.

How do you find nil in Objective-C?

length == 0) . object. length will return 0 if object == nil , so this test covers nil objects and strings with length 0. If you treat a string of length 0 different from a nil string, just check if object == nil .

WHAT IS null pointer give example?

A null pointer constant is an integer constant expression that evaluates to zero. For example, a null pointer constant can be 0, 0L , or such an expression that can be cast to type (void *)0 . You can specify any of the following values for a null pointer constant: 0.

How do you check if a pointer is empty?

An integer literal with value zero (including 0 and any valid definition of NULL ) can be converted to any pointer type, giving a null pointer, whatever the actual representation. So p != NULL , p != 0 and p are all valid tests for a non-null pointer.

How do you find nil in Objective C?

What is nil in linked list?

The null reference occurs in the link part of the final node of a linked list. A program that maintains a head and a tail reference may set these references to null, which indicates that the list is empty (has no nodes).

WHAT IS null pointer give an example?

In case with the pointers – if any pointer does not contain a valid memory address or any pointer is uninitialized, known as “NULL pointer”. We can also assign 0 (or NULL) to make a pointer as “NULL pointer”. Example: In this example, there are 3 integer pointers ptr1, ptr2 and ptr3.