C Programming Interview Questions - Continuation

"calloc(...)" and "malloc(...)" :

•  calloc(...) allocates a block of memory for an array of elements of a certain size. By  default the block is initialized to 0. The total number of memory allocated will be (number_of_elements * size).
•  malloc(...) takes in only a single argument which is the memory required in bytes. malloc(...) allocated bytes of memory and not blocks of memory like calloc(...).
•  malloc(...) allocates memory blocks and returns a void pointer to the allocated space, or NULL if there is insufficient memory available.
•  calloc(...) allocates an array in memory with elements initialized to 0 and returns a pointer to the allocated space. calloc(...) calls malloc(...) in order to use the C++ _set_new_mode function to set the new handler mode.

"printf(...)" and "sprintf(...)" :

•          sprintf(...) writes data to the character array.
•          printf(...) writes data to the standard output device.

Linked Lists :

To check whether a linked list is circular :

Create two pointers, and set both to the start of the list. Update each as follows:

while (pointer1) {

pointer1 = pointer1->next;

pointer2 = pointer2->next;

if (pointer2) pointer2=pointer2->next;

if (pointer1 == pointer2) {

print ("circular");

}

}

If a list is circular, at some point pointer2 will wrap around and be either at the item just before pointer1, or the item before that. Either way, its either 1 or 2 jumps until they meet.

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