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Pointer Review

This guide provides a comprehensive solution for managing an ordered linked list in C++. It covers the implementation of functions to insert and delete elements with specific values while ensuring the list remains ordered. This includes writing code snippets to handle edge cases, like inserting at the head or the tail of the list. Additionally, we explore memory management principles, including pointers, dynamic memory allocation, and pitfalls such as dangling pointers and memory leaks. Perfect for C++ students and developers aiming to enhance their data structure skills!

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Pointer Review

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  1. Pointer Review

  2. Node {int value; Node * next; Node( intval =-1, Node * n = NULL) {value = val; next = n;}} • Given a ordered linked list pointed to by head, write the code to insert an element with value x.

  3. Node {int value; Node * next; Node( intval =-1, Node * n = NULL) {value = val; next = n;}} • Given a ordered linked list pointed to by head, write the code to delete an element with value x.

  4. What type is a *a **a

  5. What type is a *a **a Hint: I read the declaration backwards, a is a pointer to a pointer to an int. When I look at *a, I mentally glue the *a together and think int * (*a) *a is a pointer to an int.

  6. Fill in the blanks //find and return the maximum value in an array intmaxEntry(int* data, intsize) { if ( data == NULL || size <= 0 ) return INT_MIN; int*highSoFar =________________ ; for (int count = ______; count <size;______________ ) { if ( __________________________) highSoFar= __________________; } return _____________________; }

  7. int * p;int * q; • What comparison would be true iffp and q have targets with the same value? 1) &p == &q 2) *p == *q 3) p == q

  8. Student * p;Student * q; • What comparison would be true iff p and q have the same target? 1) &p == &q 2) *p == *q 3) p == q

  9. intfoo= 17;int *ptr = &foo; • Which of the following statements will change the value of footo 18? 1) ptr++; 2) foo++; 3) (*foo)++; 4) (*ptr)++;

  10. Both code fragments below will compile but the one on the right will (on most systems) cause a runtime error. Why? Draw a picture to show what is happening. int x = 5; int *p = new int(x); delete p; int x = 5; int *p = &x; delete p;

  11. const intsize = 5;int*a = new int[size]; • What code fragment could be inserted in the blank in order to safely initialize each element of A to zero? int* p = &a[0]; for (inti= 0; i< size; i++, p++) { _____________________; } 1) *a = 0; 2) a[i] = 0; 3) *p = 0; 4) *i= 0;

  12. Definitions • 1) A dangling pointer is a pointer whose value is the address of memory that the program does not own. • 2) A memory leak is when the program owns memory that it can no longer access.

  13. const intsize = 5;int*a = new int[size]; • What logical error(s) would result if the following statement were executed? a= new int[2*size]; 1) A dangling pointer would result 2) A memory leak would result 3) Both a dangling pointer and a memory leak would result. 4) None of the above

  14. const intsize = 5;int*a = new int[size];int* p = &a[0]; • What logical error(s) would result if the following statement were executed: delete [] p; 1) A dangling pointer would result 2) A memory leak would result 3) Both a dangling pointer and a memory leak would result. 4) None of the above

  15. Show the picture after executing • p->next = q;

  16. Show the picture after executing q->next = p->next; p->next = NULL;

  17. Show the picture after executing q->next = p->next; q->next->next = p; p->next = NULL;

  18. Show the picture after executing • q->next = NULL; • delete p;

  19. Show the picture after executing • delete (p->next);

  20. Show the picture after executing • q->next = head; • delete p;

  21. Show the picture after executing • delete Head; • head = q;

  22. Given the following, explain the effect of the following on the contents of ptrand i: inti= 10,; int *ptr= &i intj = 4; *ptr+= j;

  23. Given the following declarationsint a[] = {5, 15, 34, 54, 14, 2, 52, 72};int *p = &a[1];int*q = &a[5]; • What is the value of *(p+3)?

  24. Given the following declarationsint a[] = {5, 15, 34, 54, 14, 2, 52, 72};int *p = &a[1];int*q = &a[5]; • What is the value of *(q-3)?

  25. Given the following declarationsint a[] = {5, 15, 34, 54, 14, 2, 52, 72};int *p = &a[1];int*q = &a[5]; • What is the value of q – p ?

  26. Given the following declarationsint a[] = {5, 15, 34, 54, 14, 2, 52, 72};int *p = &a[1];int*q = &a[5]; • Is the condition p < q true or false?

  27. Given the following declarationsint a[] = {5, 15, 34, 54, 14, 2, 52, 72};int *p = &a[1];int*q = &a[5]; • Is the condition *p < *q true or false?

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