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 are the various page replacement algorithms, What are the various page...

What are the various page replacement algorithms used for page replacement? FIFO page replacement Optimal page replacement LRU page replacement LRU approximat

Define logical address and physical address, Define logical address and phy...

Define logical address and physical address. An address formed by the CPU is referred as logical address. An address seen by the memory unit that is the single loaded into the

Define middleware to ease the low-level protocol burden, Define Middleware ...

Define Middleware to Ease the Low-Level Protocol Burden Fortunately, many products are available today to ease the low-level protocol burden on the application programmer. Midd

Explain the beginthread function used in the netware, Explain the BeginThre...

Explain the BeginThread Function used in the NetWare example code BeginThread(MyThread Function, stack,size, arg) BeginThread creates a thread and places it on the NetWar

Invalid page fault, Invalid page fault :If a page fault happens for a ref...

Invalid page fault :If a page fault happens for a reference to an address that's not part of the virtual address space, so that there could not be a page in memory corresponding

System structures, advantages and disadvantages of monolithic and layered a...

advantages and disadvantages of monolithic and layered approach

OS is a resource allocator and control program, why we say OS is a resource...

why we say OS is a resource allocator and control program

Example of semaphore, For example, by initializing a semaphore to 0, thread...

For example, by initializing a semaphore to 0, threads can wait for an event to occur, and impose an ordering constraint, similar to a monitor using condition variables, but with m

Independent process, what is independent process? distinguished between ind...

what is independent process? distinguished between independent process and co-operating process

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