a2zinterviews

29.	What is pointer linking with operating system?
	When we declare a null pointer it addresses the 0 address which is the address of operating system so we cannot use that address this is what the pointer is linked to OS.
	Discuss Your Name Your Email-ID Your Answer

30.	Is there a built in function in C that can be used for sorting data?
	Yes, use the qsort() function. It is also possible to create user defined functions for sorting, such as those based on the balloon sort and bubble sort algorithm.
	Discuss Your Name Your Email-ID Your Answer

31.	What does the function toupper() do?
	It is used to convert any letter to its upper case mode. Toupper() function prototype is declared in <ctype.h>. Note that this function will only convert a single character, and not an entire string.
	Discuss Your Name Your Email-ID Your Answer

32.	What is NULL in C?
	NULL is a macro which defined in C header files. The value of NULL macro is 0. It is defined in C header files as below #define NULL (void *) 0; NULL is used for pointers only as it is defined as (void *) 0. It should not be used other than pointers. If NULL is assigned to a pointer, then pointer is pointing to nothing.
	Discuss Your Name Your Email-ID Your Answer