Pointer Lecture 2 Course Name: High Level Programming Language Year : 2010

3 Learning Outcomes At the end of this lecture, students are capable of: Using pointer in C Language through an understanding of microprocessor architecture

4 Outline Material Pointer and Architecture Computer Usage Of Pointer Variable Pointer

5 Pointer and Arsitektur Komputer Pointer is an address!!! 33 k ? Uninitialized integer pointer (pointing to a random location) Null pointer (pointing to a NULL location or to a grounding location “0”) integer pointer (pointing to a variable k)

6 Pointer and Architecture Computer Function of pointer: –It can refer to one object now and a different object later Generally, a pointer in C program functions to: –Return two or more value from a function –Operate on data type string –Operate on arrays and struct –Data structure that changes size (next week)

7 Usage Of Pointer int x = 10; int *p; p = &x; *p = 20; Pointer declaration to data type integer & is an address operator that takes the address of x * dereference operator takes value from p

8 Usage Of Pointer int x = 10; int *p; p = &x; p takes the address of the variable x p x10

9 Usage Of Pointer int x = 10; int *p; p = &x; *p = 20; *p is the value inside the address p p x20

Conclusions Pointer variable contains address, not data value, always remember that! Pointer refers only to one particular object at one time, though later, it can be altered to different object. Dereference Pointer is used to access a content of a particular memory allocation. 10

11 Topic For Next Week Variable Pointer –Assignment: Read book of “CppEssentials.pdf” chapter 5 pages 65 until 79. –Do the following exercises (taken from “exercises” page 80 of book “CppEssentials.pdf”): 1. Define a function to input a list of names and store them as dynamically-allocated strings in an array, and a function to output them: void ReadNames (char *names[], const int size); void WriteNames (char *names[], const int size);

12 Topic For Next Week Continued. Write another function which sorts the list using bubble sort: void BubbleSort(char *names[], const int size); Bubble sort involves repeated scans of the list, where during each scan adjacent items are compared and swapped if out of order. A scan that involves no swapping indicates that the list is sorted.

13 Topic For Next Week 2. Rewrite the following function using pointer arithmetic: char* ReverseString (char *str) { int len = strlen(str); char *result = new char[len + 1]; for (register I = 0; I < len; ++i) result[i] = str[len – i – 1]; result[len] = ‘\0’; return result; }