C Programming - Pointers - Discussion

Is the answer is 4, 2 or 4, 1? Can anyone explain it?

As null is a null pointer and size of all pointers is same and is given 4 its size is 4 and sizeof "" is 1 since it is an empty string with '\0'.

O/P is depends on compiler:

If you run using Dev C++ then o/p: 8, 1.

Linux compiler o/p: 4, 1.

@Shraddha.

Here 4, 1 is the correct answer because of sizeof ("") --->sizeof ("\0").

So it will take an one bit value. So it will be print 1 and sizeof (NULL) ----> sizeof (null\0).

n->0.
u->1.
l->2.
l->3 and \0->4.

So the output will become into 4 and 1.

@Anjaneyareddy.

If you say so for NULL then the sizeof ("") - - >sizeof ("\0").

\0->0?

#include<stdio.h>

int main()
{
printf("%d, %d\n", sizeof(NULL), sizeof(""));
return 0;
}

I got output as 8 1.

64-bit machine.

I can't understand it please explain with an example of sizeof (NULL);.

sizeof("")

Whatever we write in double quotation marks ("") it considers as the string literal. A string literal is a sequence of characters which, taken together, form a null-terminated string.
Each character occupies 1 byte in TurboC and in Linux GCC 2 bytes.

Eg. of string literal
name = "Jack";
Each string literal ends with null-character('/0')
name = "Jack/0"

// Each character occupy 1 byte so, sizeof("Jack") = 5 including null character "Jack/0";
1 byte for each character
J = 1
a = 2
c = 3
k = 4
/0 = 5

If we write ("") means it's string literal with null character("/0").
So, sizeof("") is 1 byte.
1 byte for each character. Here only 1 character it is the null character.
so,
/0 = 1

coming on sizeof(NULL)

NULL is not pointing to anything but we can store the address of any type in place of NULL value and address always occupy two bytes because it is unsigned int. unsigned int occupies 2 bytes like int occupy 2 bytes. It is vary from one platform to another.

Windows TurboC: sizeof(NULL) = 2 and sizeof(char) or sizeof('/0') or sizeof("") = 1
Linux GCC compiler: sizeof(NULL) = 4 and sizeof(char) or sizeof('/0') or sizeof("") = 2

Thanks a lot @Rahul Chauhan.

The Size of pointer on 16- bit compiler is 2 bytes.
The Size of pointer on 32- bit compiler is 4 bytes.
The Size of blank character is 1 byte.