Understanding NULL pointer in C -


i have found in code null pointer defined follows - 

#define null ((char *)0)

i found these code compiles fine. did not understand how works. can please explain how 0 casted char pointer?

and valid use file pointer making null - 

file *fp = null;

the c library macro null value of null pointer constant.it may defined ((void*)0), 0 or 0l depending on compiler vendor. depending on compiler,declaration of null can be

#define null ((char *)0)

or

#define null 0l

or

#define null 0

and valid use file pointer making null--> yes.


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