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

Write a short note on pcb, Write a short note on PCB? Every process is ...

Write a short note on PCB? Every process is represented in the operating system by a process control block also called a task control block. It contains more information regard

Explain about directory structure, Normal 0 false false fal...

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

Deadlock prevention-resource allocation graph allocation, Explain Deadlock ...

Explain Deadlock Prevention-Resource allocation graph allocation Resource allocation graph algorithm :  Using this algorithm we are able to actually know if there exists in th

Write a note on semaphores, Write a note on semaphores A semaphore is a...

Write a note on semaphores A semaphore is a tool meant for synchronizing multiple processes trying to access a shared variable. That is a semaphore is used to deal with the cri

What is the main problem with the fcfs scheme, Question : a) Consider ...

Question : a) Consider table 1.0 below, assume the processes arrived in the order P 1 , P 2 , P 3 , P 4 at time shown and need the indicated burst time (both in milliseconds)

Define process? what is meant by state of a process?, Define process? What ...

Define process? What is meant by state of a process? Process is a program in implementation. A process in general includes the process stack, which consists temporary data and

Explain process description in the unix system, Process Description A pr...

Process Description A process in UNIX is a somewhat complex set of data structures that provides the operating system with all of the information necessary to dispatch and manag

Explain advantages and inconveniences of ult, ADVANTAGES AND INCONVENIENCES...

ADVANTAGES AND INCONVENIENCES OF ULT Advantages: Thread switching doesn't involve the kernel - no mode switching Scheduling is able to be application specific -

Explain the application interaction protocols, Explain the Application Inte...

Explain the Application Interaction Protocols Application interaction protocols are uniquely defined for each program and are used to logically describe the data being passed b

Describe the main architectural layers of windows xp, Q. Describe the three...

Q. Describe the three main architectural layers of Windows XP? Answer: (1) The HAL (Hardware Abstraction Layer) creates operating system portability by hiding hardware differ

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