Address operator and pointers, Operating System

Assignment Help:

  We are use to using variables within C without thinking about where they are stored. Most variables are dynamic i.e. can change, therefore they are stored in Ram, unlike a program once developed is static i.e. doesn't change; this is often storage in EPROM or Rom. We can directly access the address where the variable is stored by means of the address operator '&' .This returns the address of the variable followed i.e.

printf("The address of var A is %lx and the contents of var A is %x",&a,a) 
 
This address is often fixed by the compiler and cannot be altered easily, very often we want initialize the address of a variable and vary it, C uses the concept of the pointer to handle this. A pointer is a variable which holds an address (This is in fact an address register on the 68Hc11 i.e. X, Y). We can explicitly load up the variable with any number (address which we like) and perform simple mathematical functions on it i.e. add, mul, sub etc. In order to declare the variable as a pointer we need to prefix it with a * in its declarations i.e.

      int *point;  
      char *point; 
      float *point;

The type of pointer  used describes the size of the data to be read  i.e. a char pointer reads 7 bits of data , unsigned char 8 bits i.e. (some programmers use sizeof function to get actual machine size).

    char * point  == 7 bits
     unsigned char * point  == 8 bits
     int * point  == 15 bits
     unsigned int  * point  == 16 bits
     float * point  == 31 bits
     unsigned float  * point  == 32 bits


Related Discussions:- Address operator and pointers

Explain file, What is a file? A named collection of related data explai...

What is a file? A named collection of related data explained by the creator, recorded on secondary storage.

List post-installation procedures that need to be performed, Problem: (...

Problem: (a) Based on your experience in setting up Windows 2003 Server operating system, briefly describe the twelve different steps in which the installation is conducted du

Define properties of real time operating system, Define properties of Real ...

Define properties of Real time operating system Real time :- Often used in a dedicated application, this system reads information from sensors and must respond within a fixed a

If a process is blocked, There is a process bloacked by a semaphore and no ...

There is a process bloacked by a semaphore and no other process in the ready queue, can the blocked process get back to the ready queue without the semsignal() function?

Define analysis for syntactic structure of source statement, An analysis, w...

An analysis, which defines the syntactic structure of the source statement, is known as Syntax analysis defines the syntactic structure of the source statement

Write a short note about the different states of a process, Write a short n...

Write a short note about the different STATES of a process. As a process implement it changes state. The state of a process is described in part by the current activity of that

Define seek time and latency time, Define seek time and latency time. T...

Define seek time and latency time. The time taken by the head to move to the appropriate cylinder or track is known as seek time. Once the head is at right track, it must wait

Mutual exclusion, With software algorithms for mutual exclusion, such as De...

With software algorithms for mutual exclusion, such as Dekker's algorithm, Peterson's algorithm, or Lamport's bakery algorithm, note that optimizing compilers and out-of-order exec

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd