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

Requirements memory management intended to satisfy?, Normal 0 f...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

What is turnaround time, What is turnaround time? Turnaround time is th...

What is turnaround time? Turnaround time is the interval from the time of submission to the time of completion of a process. It is the sum of the periods exhausted waiting to g

Explain segmentation hardware?, Explain segmentation hardware? We defin...

Explain segmentation hardware? We define an completion to map two-dimensional user-defined addresses into one-dimensional physical addresses. This mapping is affected by means

User threads control dispatching, Consider a particular system that does no...

Consider a particular system that does not have an interrupting clock.  The only way a thread can lose the processor is to voluntarily surrender it.  Additionally, the operating sy

What is low-level formatting, What is low-level formatting? Before a di...

What is low-level formatting? Before a disk can kept data, it must be required into sectors that the disk controller can read and write. This procedure is called low-level form

What is the main difficulty real-time environment, What is the main difficu...

What is the main difficulty that a programmer must overcome in writing an operating system for a real-time environment? The main difficulty is keeping the operating system with

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

What is real time system, What is real time system? A real time system ...

What is real time system? A real time system has well explained, fixed time constraints. Processing must be done within the explained constraints, or the system will fail. It i

Hashed page table, W hat is hashed page table & method of hashed page tabl...

W hat is hashed page table & method of hashed page table with details

Socket, socket based fortune teller sever.your program should create a serv...

socket based fortune teller sever.your program should create a server that listens to a specific port when a client receives a connection the server should respond with a random fo

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