NUL undeclared- first use in this function

Question

From the web I understand that C contains NUL keyword.

But while compiling I get an error

NUL undeclared first use in this function\'
         


        

Answer 1

It's NULL, not NUL.

EDIT

Did you even read the link you posted? It says very specifically "NULL is not NUL. NUL is not a defined keyword in C++"

NULL is a macro defined in 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 ??.