What is null in C programming?

At the very high level, we can think of NULL as a null pointer which is used in C for various purposes. Some of the most common use cases for NULL are a) To initialize a pointer variable when that pointer variable isn’t assigned any valid memory address yet. b) To check for a null pointer before accessing any pointer variable.

What is a null pointer in C11?

From C11 standard clause 6.3.2.3, “ An integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant. If a null pointer constant is converted to a pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function.

Why can’t I return Null from a function?

If you’re returning null, you’re creating a source of bugs, and you are miscommunicating the intention of your function/method. Second, if for any reason you are doing this: You’re clearly doing it wrong. If an argument is optional, you can create a method overload (as one simple solution).

What happens when a null pointer is converted to a pointer?

If a null pointer constant is converted to a pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function.

Can We set a null pointer to 0 in C++?

Neither in C nor in C++ null-pointer value is in any way tied to physical address 0. The fact that you use constant 0in the source codeto set a pointer to null-pointer value is nothing more than just a piece of syntactic sugar.

What happens when you free a pointer in C?

From section 7.20.3.2/2 of the C99 standard: The free function causes the space pointed to by ptr to be deallocated, that is, made available for further allocation. If ptr is a null pointer, no action occurs.

What is the internal value of a null pointer in C?

But again, as a C programmer, we needn’t worry much on the internal value of the null pointer unless we are involved in Compiler coding or even below the level of coding. Having said so, typically NULL is represented as all bits set to 0 only. To know this on a specific platform, one can use the following