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

Describe the purpose of the checkpoint mechanism, Describe the purpose of t...

Describe the purpose of the checkpoint mechanism. How habitually must checkpoints be performed? Explain how the frequency of checkpoints affects: System performance while no

What is the purpose of the virtual memory in windows xp, Question: a) T...

Question: a) The following refers to optimization under Windows XP: i) Give five steps which could undertake to enhance overall system performance in a default Windows XP in

Define the turn-around time of a user job, Define the “turn-around” time of...

Define the “turn-around” time of a user job Turn- around time is total time taken to execute the job.

Explain contiguous allocation, Contiguous allocation The contiguous-all...

Contiguous allocation The contiguous-allocation method needs each file to occupy a set of contiguous blocks of the disk. Disk addresses explain a linear ordering on the disk. T

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.

Dual mode operation, WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF DUAL MODE...

WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF DUAL MODE OPERATION OF OPERATING SYSTEM>?

What is erd, What is ERD? Entity Relationship Diagram is the graphical ...

What is ERD? Entity Relationship Diagram is the graphical representation of the object relationship pair. It is mostly used in database applications.

Explain the scheduleworktodo function used in netware, Explain the Schedule...

Explain the ScheduleWorkToDo Function used in Netware ScheduleWorkToDo(MyThread Function, arg, workToDo) The ScheduleWorkToDo ( ) function is specific to NetWare 4.0. This c

Sector sparing, What is sector sparing is proper definition

What is sector sparing is proper definition

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