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

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

Write a note about directory structure with examples., Write a note about ...

Write a note about Directory structure with examples. The FreeBSD directory hierarchy is basic to obtaining an overall understanding of the system. The most significan

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

wat are the commands used for creating the file hierarchy

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

Parent and child process communicate in unix, Parent and Child process comm...

Parent and Child process communicate in unix A child and parent can interact through any of the normal  inter-process communication schemes (pipes, message queues, sockets, s

Student, Explain how the os implements virtual memory phenomenon.

Explain how the os implements virtual memory phenomenon.

Tlb replacement algorithm, Suppose a logical address space is 1KB, and the ...

Suppose a logical address space is 1KB, and the page-size is 16 bytes. Assume no page is in the main memory for this process initially and the pure demand paging is used. Current f

Define computer system environment, Q. List three instances of deadlocks th...

Q. List three instances of deadlocks that aren't related to a computer system environment. Answer: Two cars passage a single-lane bridge from opposite directions.

Most-recently used algorithm, Evicting the most-recently used (MRU) page do...

Evicting the most-recently used (MRU) page does very well on LRU's worst case. In general, however, MRU is a bad idea, since many programs exhibit temporal locality in their memory

Communications technique - application interaction protocols, Define the Co...

Define the Communications Techniques - Application interaction protocols    Communications techniques are well defined. They give developer the programmatic mechanism to transf

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