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

Explain lru second chance algorithm, Second chance Algorithm When the p...

Second chance Algorithm When the page is chosen the reference bit is checked to see whether it has been referenced before. If that is the case after that it is given a second c

What is a semaphore, What is a semaphore? A semaphore 'S' is a synchron...

What is a semaphore? A semaphore 'S' is a synchronization tool which is  an integer value that, apart from initialization, is accessed only by two standard atomic operations; w

Three conditions that solution for critical section problem, What are three...

What are three conditions that a solution for the critical section problem must satisfy? The three conditions are as following:- a)      Mutual exclusion :- if a process is

Determine the minimum number of units of resource, An operating system invo...

An operating system involves 3 user processes each one requiring 2 units of resource R .The minimum number of units of R like no deadlocks will ever take place is The minimum

Under what circumstances do page faults occur, Under what circumstances do ...

Under what circumstances do page faults occur?  Describe the actions taken by the operating system when a page fault occurs. A page fault happens when an access to a page that

System service program, System Service Program system service program S...

System Service Program system service program Supports and provides the services for other program. System service program perform Varity of tasks.  They are further divided in

Inventory differences, What makes a Just-in-Time inventory system differ fr...

What makes a Just-in-Time inventory system differ from a traditional inventory system?

Definition of operating system, Q. Definition of Operating System? Defi...

Q. Definition of Operating System? Definition of Operating System: • An Operating system is a program which controls execution of application programs and acts as an interfa

Linux OS, Ask questioDevelop a utility in C language which will run in Linu...

Ask questioDevelop a utility in C language which will run in Linux operating systems to display following properties of the system: ? Processor speed ? Ram size ? Computer name ? S

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