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 the different paging techniques, The different paging techniques are ...

The different paging techniques are 1. Multilevel paging or hierarchical paging method: In definite cases the page table may consist up to 1 million entries. This would be

What are the phases of background processing, What are the phases of backgr...

What are the phases of background processing? Phases are:- Job Scheduling. Job Processing. Job Overview.

Why do systems stay track of the type of a file, Q. Why do some systems sta...

Q. Why do some systems stay track of the type of a file while others leave it to the user or simply don't implement multiple file types? Which system is "better?" Answer: A f

Prepare a short note on the standard linux file system, Problem: a) Pre...

Problem: a) Prepare a short note on the standard Linux File System. b) Prepare a short note on the RPM Package Management Tool. c) Briefly explain the two types of login

Explain the novell netware, Explain the Novell NetWare     NetWare does...

Explain the Novell NetWare     NetWare doesn't really have the concept of processes in the architecture, as  the most closely associated element in the NetWare  environment to

What is direct memory access, Direct memory access Many computers avoid...

Direct memory access Many computers avoid burdening the main CPU with programmed I/O by offloading sine if this work to a special-purpose processor known as a direct memory add

Explain process scheduling, Explain Process scheduling Process scheduli...

Explain Process scheduling Process scheduling consists of the subsequent sub-functions: 1.      Scheduling : Selects the process to be implement next on the CPU 2.      D

What are the various file operations, What are the various file operations?...

What are the various file operations? The six basic file operations are Creating a file Reading a file Writing a file Repositioning within a file Tr

Linux, write a linux command to display lines from 25 - 45 of directory "/e...

write a linux command to display lines from 25 - 45 of directory "/edc/password" write a linux command to display directory in /edc

Linux, what is I/O management Linux

what is I/O management Linux

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