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

Design a android application, As mentioned earlier, the game engine will b...

As mentioned earlier, the game engine will be used as the base of developing the Go game for the Android. This includes improving logic of the game, design good graphics and optim

Explain a computing environment, Q. Polling for an I/O completion is able ...

Q. Polling for an I/O completion is able to waste a large number of CPU cycles if the processor iterates a busy-waiting loop several times before the I/O completes. However if the

Os structures, #question.explain varios types of system calls..

#question.explain varios types of system calls..

Components of the r/e system, What components of the R/e system initiate th...

What components of the R/e system initiate the start of background jobs at the specified time? The batch scheduler initiates the begin of background job.  The dispatcher then s

What do you mean by first fit, What do you mean by first fit? First fit...

What do you mean by first fit? First fit allocates the first hole that is big sufficient .Searching can either start at the starting of the set of holes or where the previous f

CPU Scheduing FCFS, Assume that P A , P B and P C are three distinguished p...

Assume that P A , P B and P C are three distinguished program s . When P A is executed, it needs 10 ticks to complete its execution and it forks new processes executing P B at tick

Demand paging, Demand paging With demand paging, a page is called into...

Demand paging With demand paging, a page is called into memory only when a location on that page is actually indexed during run time. With pre-paging, pages other than the one

Advanced synchronization, Synchronization serves two purposes: 1) to ensure...

Synchronization serves two purposes: 1) to ensure safety for updates on shared data (e.g. to avoid races conditions), and 2) to coordinate and order actions taken by threads (e.g.

Explain independent process and a cooperating process, Question: a) Ea...

Question: a) Each process is represented in the operating system by a process control block (PCB). The PCB contains many pieces of information associated with a specific proce

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