Programming Fundamentals

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1511 fetch-activity list_insert_nth

Your task is to add code to this function in list_insert_nth.c: 

// Insert a new node containing value at position n of the linked list.
// if n == 0, node is inserted at start of list
// if n >= length of list, node is appended at end of list
// The head of the new list is returned.
struct node *insert_nth(int n, int value, struct node *head) {
    // PUT YOUR CODE HERE! CHANGE THE NEXT LINES!
    return NULL;
}

insert_nth is given three arguments, n value and head

Add code to insert_nth so that it creates a new list node (using malloc) containing value and places it before position n of the list.

The elements are counted in the same manner as array elements (zero-based), so the first element in the list is regarded as at position 0, the second element position 1 and so on.

If there are less than n elements in the list, the new list node should be appended to the end of the list.

insert_nth should return a pointer to the new list.

For example if n is 1 and value is 12 and the linked list contains these 3 elements:

16, 7, 8

insert_nth should return a pointer to a list with these elements:

16, 12, 7, 8

Testing

list_insert_nth.c also contains a main function which allows you to test your insert_nth function.

This main function:

  1. Asks for the size of the linked list,
  2. asks for standard input to convert to a linked list,
  3. assigns a pointer to the first node in the linked list to head,
  4. reads an integer from standard input and assigns it to n,
  5. reads a second integer from standard input and assigns it to value
  6. calls insert_nth(n, value, head) and
  7. prints the result.

Do not change this function. If you want to change it, you have misread the question.

Your insert_nth function will be called directly in marking. The main function is only to let you test your insert_nth function

dcc list_insert_nth.c -o list_insert_nth
./list_insert_nth
How many numbers in initial list?: 3
16 7 8
Enter position and value to insert: 0 12
[12, 16, 7, 8]
./list_insert_nth
How many numbers in initial list?: 3
16 7 8
Enter position and value to insert: 1 12
[16, 12, 7, 8]
./list_insert_nth
How many numbers in initial list?: 3
16 7 8
Enter position and value to insert: 2 12
[16, 7, 12, 8]
./list_insert_nth
How many numbers in initial list?: 3
16 7 8
Enter position and value to insert: 3 12
[16, 7, 8, 12]
./list_insert_nth
How many numbers in initial list?: 3
16 7 8
Enter position and value to insert: 42 12
[16, 7, 8, 12]
./list_insert_nth
How many numbers in initial list?: 1
42
Enter position and value to insert: 0 16
[16, 42]
./list_insert_nth
How many numbers in initial list?: 0
Enter position and value to insert: 0 2
[2]
./list_insert_nth
How many numbers in initial list?: 0
Enter position and value to insert: 10 2
[2]

Assumptions/Restrictions/Clarifications