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

Difference between threads and processes, Difference between threads and pr...

Difference between threads and processes 1. Thread is flow of implementation. Process is group of instruction which is alike to that of a program except which may be stopped an

Define different multithreading models, DIFFERENT MULTITHREADING MODELS ...

DIFFERENT MULTITHREADING MODELS Multithreading Models the majority multithreading models fall into one of the following categories of threading implementation: 1.      M

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

Describe the purpose of the open and close operations, Q. Describe the pur...

Q. Describe the purpose of the open() and close() operations. Answer: The open() operation notifies the system that the named file is about to become active. The c

Batch oriented and interactive operating system., properies of Batch orient...

properies of Batch oriented and interactive operating system.

Paging, what is the use of valid invalid bits in paging

what is the use of valid invalid bits in paging

Define most common phase structured grammar, Which is most common phase str...

Which is most common phase structured grammar? Most common phase structured grammar is Context – Sensitive

Explain debugging a multi threaded program, Debugging a multi threaded prog...

Debugging a multi threaded program The following list points out few of the more frequent oversights and errors that can cause bugs in multithreaded programs. 1.    Ephemeral

Transfer time, A hard-disk drive reads “120 GB HDD 7200 rpm 3 GB/sec transf...

A hard-disk drive reads “120 GB HDD 7200 rpm 3 GB/sec transfer rate”. If the drive has a sector size of 512 bytes, what is the average rotational latency and transfer time to read

Explain terminal symbols, Explain Terminal Symbols Terminal symbols are...

Explain Terminal Symbols Terminal symbols are literal strings that are forming the input of a formal grammar and cannot be broken down into smaller units with no losing their l

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