Common questions WHAT IS null pointer explain with example?

WHAT IS null pointer explain with example?

WHAT IS null pointer explain with example?

A Null Pointer is a pointer that does not point to any memory location. 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 null pointer assignment?

A NULL pointer assignment is a runtime error It occurs due to various reasons one is that your program has tried to access an illegal memory location. Illegal location means either the location is in the operating systems address space or in the other processes memory space.

How do you write a null pointer?

Declare a pointer p of the integer datatype. Initialize *p= NULL. Print “The value of pointer is”. Print the value of the pointer p.

Can you assign a value to a null pointer?

In C programming language a Null pointer is a pointer which is a variable with the value assigned as zero or having an address pointing to nothing. So we use keyword NULL to assign a variable to be a null pointer in C it is predefined macro.

What type of error is a null pointer?

A NULL pointer dereference is a sub type of an error causing a segmentation fault. It occurs when a program attempts to read or write to memory with a NULL pointer. Running a program that contains a NULL pointer dereference generates an immediate segmentation fault error.

Is null a mistake?

This exception for a singular NUL character has caused innumerable errors: API weirdness, security vulnerabilities, and buffer overflows. NULL is the worst CS mistake; more specifically, NUL-terminated strings are the most expensive one-byte mistakes.

IS NULL check bad?

Because NPE’s are typically from bad searches, and that there are ways to circumvent these failures that incorporate good coding practices, that null checks are sometimes considered bad habit. The best way to avoid NPE’s is to never allow a null to be assigned with good coding habits.

What can a null pointer be used for?

A null pointer is a pointer which points nothing. Some uses of the null pointer are: a) To initialize a pointer variable when that pointer variable isn’t assigned any valid memory address yet.

Do you always initialize pointers as null in C?

Inspite of mentioning machine dependent stuff as above, we as C programmers should always strive to make our code as portable as possible. So we can conclude on NULL as follows: 1. Always initialize pointer variables as NULL. 2. Always perform a NULL check before accessing any pointer. Please do Like/Tweet/G+1 if you find the above useful.

Where can I find the null pointer constant?

Strictly speaking, NULL expands to an implementation-defined null pointer constant which is defined in many header files such as “ stdio.h ”, “ stddef.h ”, “ stdlib.h ” etc. Let us see what C standards say about null pointer.

What is the value of null in C?

The word “NULL” is a constant in C language and its value is 0. 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”.