31. What are the facilities provided by preprocessor?
Ans:
1-file inclusion
2-substitution facility
3-conditional compilation
32. What are the differences between malloc () and calloc ()?
Ans: Malloc Calloc 1-Malloc takes one argument Malloc(a);where a number of bytes 2-memory allocated contains garbage values
1-Calloc takes two arguments Calloc(b,c) where b no of object and c size of object
2-It initializes the contains of block of memory to zerosMalloc takes one argument, memory allocated contains garbage values.
It allocates contiguous memory locations. Calloc takes two arguments, memory allocated contains all zeros, and the memory allocated is not contiguous.
Ans:
1-file inclusion
2-substitution facility
3-conditional compilation
32. What are the differences between malloc () and calloc ()?
Ans: Malloc Calloc 1-Malloc takes one argument Malloc(a);where a number of bytes 2-memory allocated contains garbage values
1-Calloc takes two arguments Calloc(b,c) where b no of object and c size of object
2-It initializes the contains of block of memory to zerosMalloc takes one argument, memory allocated contains garbage values.
It allocates contiguous memory locations. Calloc takes two arguments, memory allocated contains all zeros, and the memory allocated is not contiguous.
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33. Difference between strdup and strcpy?
Ans: Both copy a string. strcpy wants a buffer to copy into. strdup allocates a buffer using malloc().
Unlike strcpy(), strdup() is not specified by ANSI .
34. What is recursion?
Ans: A recursion function is one which calls itself either directly or indirectly it must halt at a definite point to avoid infinite recursion.
Ans: Both copy a string. strcpy wants a buffer to copy into. strdup allocates a buffer using malloc().
Unlike strcpy(), strdup() is not specified by ANSI .
34. What is recursion?
Ans: A recursion function is one which calls itself either directly or indirectly it must halt at a definite point to avoid infinite recursion.
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35. What is the difference between Strings and Arrays?
Ans: String is a sequence of characters ending with NULL .it can be treated as a one dimensional array
of characters terminated by a NULL character.
36. What is a huge pointer?
Ans: Huge pointer is 32bit long containing segment address and offset address. Huge pointers are
normalized pointers so for any given memory address there is only one possible huge address segment: offset pair. Huge pointer arithmetic is doe with calls to special subroutines so its arithmetic slower than any other pointers.
37. In C, why is the void pointer useful? When would you use it?
Ans: The void pointer is useful because it is a generic pointer that any pointer can be cast into and
back again without loss of information.
38. What is generic pointer in C?
Ans: In C void* acts as a generic pointer. When other pointer types are assigned to generic pointer,
conversions are applied automatically (implicit conversion).
39. What is dynamic memory allocation?
Ans: A dynamic memory allocation uses functions such as malloc() or calloc() to get memory dynamically. If these functions are used to get memory dynamically and the values returned by these function are assigned to pointer variables, such a way of allocating memory at run time is known as dynamic memory allocation.
40. Why is it necessary to give the size of an array in an array declaration?
Ans: When an array is declared, the compiler allocates a base address and reserves enough space in
memory for all the elements of the array. The size is required to allocate the required space and hence size must be mentioned.
Ans: String is a sequence of characters ending with NULL .it can be treated as a one dimensional array
of characters terminated by a NULL character.
36. What is a huge pointer?
Ans: Huge pointer is 32bit long containing segment address and offset address. Huge pointers are
normalized pointers so for any given memory address there is only one possible huge address segment: offset pair. Huge pointer arithmetic is doe with calls to special subroutines so its arithmetic slower than any other pointers.
37. In C, why is the void pointer useful? When would you use it?
Ans: The void pointer is useful because it is a generic pointer that any pointer can be cast into and
back again without loss of information.
38. What is generic pointer in C?
Ans: In C void* acts as a generic pointer. When other pointer types are assigned to generic pointer,
conversions are applied automatically (implicit conversion).
39. What is dynamic memory allocation?
Ans: A dynamic memory allocation uses functions such as malloc() or calloc() to get memory dynamically. If these functions are used to get memory dynamically and the values returned by these function are assigned to pointer variables, such a way of allocating memory at run time is known as dynamic memory allocation.
40. Why is it necessary to give the size of an array in an array declaration?
Ans: When an array is declared, the compiler allocates a base address and reserves enough space in
memory for all the elements of the array. The size is required to allocate the required space and hence size must be mentioned.
