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

Define properties of time sharing operating system, Define properties of Ti...

Define properties of Time sharing operating system Time sharing:- T his systems uses CPU scheduling and multiprogramming to provide economical interactive use of a system. The

Case studies, Did Abhinav agree to the initial timeline requested by Rebecc...

Did Abhinav agree to the initial timeline requested by Rebecca

Main advantage of the layered approach to system design, What is the main a...

What is the main advantage of the layered approach to system design? As in all cases of modular design, designing an operating system in a modular way has several benefits. Th

Define the dossleep(ms) function used in the os/2, Define the DosSleep(ms) ...

Define the DosSleep(ms) Function used in the os/2 DosSleep()  suspends the currently executing  thread for some time interval specified in the  ms parameter. If a value of 0 is

Define seek time and latency time, Define seek time and latency time. T...

Define seek time and latency time. The time taken by the head to move to the appropriate cylinder or track is known as seek time. Once the head is at right track, it must wait

What do you meant by the term ergonomics, Question 1: "Three entities m...

Question 1: "Three entities must be accountable and responsible for accident prevention." (a) List and explain these three entities. (b) Discuss the role of workers in ma

Estimation the number of input - output per second, Q. Remapping of bad bl...

Q. Remapping of bad blocks by sector sparing or else sector slipping could influence performance. Presume that the drive in Subsequent Exercise has a total of 100 bad sectors at r

What is the purpose of the command interpreter, What is the purpose of the ...

What is the purpose of the command interpreter? Why is it usually separate from the kernel? It reads commands from the user or from a file of commands and executes them, usuall

Write pseudo code to implement the pthread create wrapper, Write pseudo cod...

Write pseudo code to implement the pthread_create wrapper of the Tern memoizer. Note you need to describe your data structure for maintaining deterministic thread IDs. In addition,

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