C Programming - Pointers - Discussion
Discussion Forum : Pointers - General Questions (Q.No. 3)
3.
In which header file is the NULL macro defined?
Answer: Option
Explanation:
The macro "NULL" is defined in locale.h, stddef.h, stdio.h, stdlib.h, string.h, time.h, and wchar.h.
Discussion:
48 comments Page 3 of 5.
Ganesh said:
1 decade ago
Both are very different.
NULL macro is
#define NULL 0
It means the macro NULL will be replaced by 0 while pre-processing. But the NULL pointer means it points to nowhere i.e. contains 0. It contains 0 means it may be dangerous to use such pointer without assigning proper address to it otherwise NULL pointer may try to access reset address may cause the program to crash.
NULL macro is
#define NULL 0
It means the macro NULL will be replaced by 0 while pre-processing. But the NULL pointer means it points to nowhere i.e. contains 0. It contains 0 means it may be dangerous to use such pointer without assigning proper address to it otherwise NULL pointer may try to access reset address may cause the program to crash.
Ganesh said:
1 decade ago
There's no reason. NULL is more commonplace whereas 0 looks like an
integer, but people use both ways all the time.
I think in C NULL is defined as 0. In C++ it is (void*)0.
integer, but people use both ways all the time.
I think in C NULL is defined as 0. In C++ it is (void*)0.
Akbar said:
1 decade ago
The <stddef.h> header defines the following: NULL: Null pointer constant. offsetof(type, member-designator): Integral constant expression of type size_t, ...
Prutha said:
1 decade ago
What is the use of null macro? why is an empty pointer required?
Om prakash said:
1 decade ago
Include any one of the header files stdio.h or stddef.h, it is enough to use NULL.
Anyhow, including the both header files stdio.h and stddef.h WILL NOT create any problem.
Anyhow, including the both header files stdio.h and stddef.h WILL NOT create any problem.
Deependra rathore said:
1 decade ago
stddef.h is stands for standard definition called it is uses for some exceptional condition
Riya said:
1 decade ago
Thnks bijan.
Bijan said:
1 decade ago
NULL Macro is simply what is defined as 0 in a macro provided by the library
Null macro is defined in stdio.h and stddef.h.It is used to represent a null pointer in your code.
its value is zero.
Null pointer is same as an uninitialized pointer..It does not point anywhere.
Null macro is defined in stdio.h and stddef.h.It is used to represent a null pointer in your code.
its value is zero.
Null pointer is same as an uninitialized pointer..It does not point anywhere.
Swetha said:
1 decade ago
Hi, please give me explanation clearly.
Zoaib said:
1 decade ago
Hi please tell about the stdio.h and stdio.lib ?
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers