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

What is preallocation, What is preallocation? Why do it? Allocating spa...

What is preallocation? Why do it? Allocating space for a file before making the file to allow for expansion. This reserves space for a certain file so that other files can't gr

Dual Mode Operation, I am not getting what you have tried to describe here....

I am not getting what you have tried to describe here. Can you elaborate more about this, i will be thankful to you. Vinay

Explain User-level threads (ult), USER-LEVEL THREADS (ULT) In this lev...

USER-LEVEL THREADS (ULT) In this level the kernel isn't aware of the existence of threads -- All thread management is complete by the application by using a thread library. Th

What is a dispatcher, What is a Dispatcher? The dispatcher is the modul...

What is a Dispatcher? The dispatcher is the module that gives control of the CPU to the process selected by the short- term scheduler. This function includes: Switching

Medium term scheduler, Medium term scheduling is form of the swapping ope...

Medium term scheduling is form of the swapping operation. This attaches to processes that are in a suspended or blocked state. They are swapped out of real-memory storage until t

Hi, is the operating system windows sometimes interupts

is the operating system windows sometimes interupts

Explain combined ult/klt approaches, COMBINED ULT/KLT APPROACHES Idea i...

COMBINED ULT/KLT APPROACHES Idea is to merge the best of both approaches Solaris is an illustration of an OS that combines both ULT and KLT  Thread creation complete i

Control the access of the three global variables, Give a brief introduction...

Give a brief introduction about the operation of your program and show that you understand the idea behind threads and mutual exclusion variable. Why do we need to use mutual exclu

Explain swapping, Explain Swapping Swapping is a method of temporarily ...

Explain Swapping Swapping is a method of temporarily removing inactive programs from the memory of computer system.

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