Which one of the following represents a correct and safe declaration of NULL ?

A) typedef((void *)0) NULL;
b) typedef NULL(char *)0;
c) #define NULL((void *)0)
d) #define NULL((char*)0)

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Jul 23rd, 2005
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Showing Answers 1 - 20 of 20 Answers

Ranjit

Apr 25th, 2005

option b is correct answer

pallavi

Jul 23rd, 2005

#define NULL((void *)0)

vivek

Mar 6th, 2007

NULL is a character, so how can it be declared as a macro with data type as void ?
please reply if you know the exact explanation to your point
waiting for your reply!

Shrishail

Jul 23rd, 2007

typedef((void *)0) NULL; can also be the correct one since NULL is a value that is assigned to pointers. The above declaration shall be good for generic data types.

Sabik

Aug 17th, 2007

#define NULL 0 is enough. NULL should be used as pointer. To be on the safer side, so that NULL wont be used as constant 0, we define #define NULL((void *)0). Then if we assign int x =NULL, it would give a compilation error