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 segmentation and paging, Why are segmentation and paging sometimes ...

Why are segmentation and paging sometimes combined into one scheme? Segmentation and paging are often combined in order to improve upon each other. Segmented paging is helpful

Explain how the system can deal with the starvation problem, Q. Can a syste...

Q. Can a system detect that some of its processes are starving? If you answer "yes," explain how it can. If you answer "no," explain how the system can deal with the starvation pro

Explain types of file allocation-contiguous allocation, Contiguous allocati...

Contiguous allocation: Every file will be allocated contiguous space in the memory. Allow the block size be 1K If a 50K files desires to be allocated space after t

Student, Explain how the os implements virtual memory phenomenon.

Explain how the os implements virtual memory phenomenon.

Program of calculator and controller - fork, Program of Calculator and Con...

Program of Calculator and Controller with the fork, exec, and wait system calls The objective of this assignment is to get you to be comfortable with the fork(), exec(), and wai

Operating system.., What is the use of FIFOs in client-server applications

What is the use of FIFOs in client-server applications

Explain the advantage of assembly language, Explain the Advantage of Assemb...

Explain the Advantage of Assembly Language The advantages of assembly language program is: a)    Reduced errors  b)    Faster translation times  c)    Changes could be ma

Define a layer that is not of an io management module, Define a layer that ...

Define a layer that is not of an IO management module  MCS that is Management Control System is not of an IO management module

Define coding in an independent service architecture, Define Coding in an i...

Define Coding in an independent service architecture Coding in an independent service architecture alleviates many of the traditional dependencies of monolithic applications.

What is an operating system process, What is an operating system process? H...

What is an operating system process? How is it different from a program? Why do we need the concept of a process, rather than simply talk about programs running in memory? The e

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