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

FUNDAMENTAL OF OS, WHAT IS OPERATING SYSTEM ?ENLIST AND EXPLAIN BASIC SERVI...

WHAT IS OPERATING SYSTEM ?ENLIST AND EXPLAIN BASIC SERVICES PROVIDE BY OS

Processes and programs, Processes and Programs Process is a dynamic...

Processes and Programs Process is a dynamic entity which is a program in execution. A process is a sequence of information executions. Process exists in a limited span of t

Explain about threading issues, Explain about threading issues? The for...

Explain about threading issues? The fork and exec system calls In a multithreaded program of few UNIX systems have chosen to have two versions of fork, one that duplicates e

Differences among user-level threads and kernel-level thread, Q. What are t...

Q. What are two differences among user-level threads and kernel-level threads? Under what situations is one type better than the other? Answer: (1) User-level threads are un

Thread, Explain thread in details

Explain thread in details

Locks - mutexes, Locks (also known as mutexes, short for mutual exclusion l...

Locks (also known as mutexes, short for mutual exclusion locks) provide mutual exclusion to shared data inside a critical session. They are implemented by means of two atomic routi

Linux operation system, wat are the commands used for creating the file hie...

wat are the commands used for creating the file hierarchy

What is a real-time system?, What is a Real-time system? A Real-time sy...

What is a Real-time system? A Real-time system is used when inflexible time requirements have placed on the operation of processor or the flow of data so it is often used as a

Thread pools, Another solution then would be to keep a pool of threads. Whe...

Another solution then would be to keep a pool of threads. Whenever a new task arrives, the system would simply get a thread from pool and set that thread to work on the given task.

Explain the spawnvp function used in the netware, Explain the Spawnvp Funct...

Explain the Spawnvp Function used in the netware Spawnvp(flags, execNmae, argv)   This function executes  similarly to spawnlp( ) except that parameters are passed as a v

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