The first line causes the compiler to reserve a space in memory for an integer. The second line tells the compiler to reserve space to store a pointer. A pointer is a storage location for an address. The third line should remind you the scanf statements

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Let us examine the following statements:

int var_x;
int* ptrX;
var_x = 6;
ptrX = &var_x;
*ptrX = 12;
printf("value of x : %d", var_x);

The first line causes the compiler to reserve a space in memory for an integer. The second line tells the compiler to reserve space to store a pointer.

A pointer is a storage location for an address. The third line should remind you the scanf statements. The address "&" operator tells compiler to go to the place it stored var_x, and then give the address of the storage location to ptrX.

The asterisk * in front of a variable tells the compiler to dereference the pointer, and go to memory. Then you can make assignments to variable stored at that location. You can reference a variable and access its data through a pointer. Let us see an example of pointers:

/* illustration of pointer use */
#include <stdio.h>

int main()
{

int index, *pt1, *pt2;

index = 39; /* any numerical value */
pt1 = &index; /* the address of index */
pt2 = pt1;

printf("The value is %d %d %d\n", index, *pt1, *pt2);

*pt1 = 13; /* this changes the value of index */

printf("The value is %d %d %d\n", index, *pt1, *pt2);

return 0;
}

The output of the program will be displayed as follows:

The value is 39 39 39
The value is 13 13 13

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Data Recovery Book
 
Chapter 1 An Overview of Data Recovery
Chapter 2 Introduction of Hard Disks
Chapter 3 Logical Approach to Disks and OS
Chapter 4 Number Systems
Chapter 5 Introduction of C Programming
Chapter 6 Introduction to Computer Basics
Chapter 7 Necessary DOS Commands
Chapter 8 Disk-BIOS Functions and Interrupts Handling With C
Chapter 9 Handling Large Hard Disks
Chapter 10 Data Recovery From Corrupted Floppy
Chapter 11 Making Backups
Chapter 12 Reading and Modifying MBR with Programming
Chapter 13 Reading and Modifying DBR with Programming
Chapter 14 Programming for “Raw File” Recovery
Chapter 15 Programming for Data Wipers
Chapter 16 Developing more Utilities for Disks
Appendix Glossary of Data Recovery Terms
 
 
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