What is the difference between NULL and NUL?

NULL is a macro defined in <stddef.h> for the null pointer. NUL is the name of the first character in the ASCII character set. It corresponds to a zero value. There�s no standard macro NUL in C, but some people like to define it. The digit 0 corresponds to a value of 80, decimal. Don�t confuse the digit 0 with the value of �� (NUL)! NULL can be defined as ((void*)0), NUL as ��.

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abhimanipal
Profile Answers by abhimanipal

Jan 30th, 2010

When we have a pointer variable of the sort
char* p

We often want to initialize it to 0, to ensure it does not point anywhere. We do this by
char* p=0

Many programmers do not feel comfortable with the fact that 0 has to meanings in the program. The decimal number 0 and the adress 0. So we achieve the above by writing
char* p= NULL

NULL is defined in the header files and is represented as ((void*)0)

NUL character is a character which has ACII value 0. It is used to indicate the end of the string.

So in a nutshell NULL is an address and NUl is a character.
To prove my point run this example

int main(int argc, char* argv[])
{
printf("%d %dn",sizeof(''),sizeof(NULL));
}

More information can be found here

http://en.wikipedia.org/wiki/Null_character