Where is null declared c

So to avoid such situations we use null pointers where variables are assigned or declared as NULL or zero which is known as a null pointer. Explanation: In the above code, we are defining function func where we are passing a pointer ptrvarA and when the function func is called it checks if the passed pointer is a null pointer or not. So we have to check if the passed value of the pointer is null or not because if it is not assigned to any value it will take the garbage value and it will terminate your program which will lead to the crashing of the program.

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. And we should note that once the data is not in use the memory allocated to it must be freed else it will again lead to the dangling pointer.

And also note that never declare any pointer without assigning NULL because the program when executes it throws an error during runtime. This is a guide to Null pointer in C. Here we discuss how Null pointer work in C with syntax and examples to implement with proper codes and outputs. You can also go through our other related articles to learn more —.

On some implementations, iostream may include cstddef, so including iostream would also give you NULL. This is mentioned in Table , Section C. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Ask Question. Asked 9 years, 2 months ago. Active 4 years ago.

Viewed 61k times. Improve this question. Always perform a NULL check before accessing any pointer. Also, please do leave us to comment for further clarification or info. Skip to content. Change Language. Related Articles. Table of Contents. Save Article. Improve Article. Like Article. Next Function Pointer in C. Recommended Articles. Article Contributed By :. To quote cppreference with a code example :.

Interestingly, this code produces the same results. Quoting from cppreference :. A null pointer constant may be implicitly converted to any pointer type; such conversion results in the null pointer value of that type.

Recall our emphasis on NULL 0 being defined as an int literal value. The example case below is not a common use case, but it demonstrates the dangers of NULL being defined as an int.