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 a client server system, What is a client server system? Central...

What is a client server system? Centralized systems proceed as server systems to satisfy request generated by client systems Server system is able to be broadly div

Requirements memory management intended to satisfy?, Normal 0 f...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Process destruction, Most process abstractions support processes being dest...

Most process abstractions support processes being destroyed when the program terminates, or in response to a specific kill directive. There are two common implementations, one a "p

What is the purpose of system calls, Q. What is the purpose of system calls...

Q. What is the purpose of system calls? Answer: System calls permit user-level processes to request services of the operating system.

What is an effector process, What is an effector process? The effector ...

What is an effector process? The effector process is a method that verifies itself.The effector process exists in particular criteria.

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

Operating System, my Operating System is windows trust but when the windows...

my Operating System is windows trust but when the windows start say its windows xp. help pleaes

How relocation bits used by relocating loader are specified, Relocation bit...

Relocation bits employed by relocating loader are specified by Relocation bits employed by relocating loader are specified by Assembler or Translator

Determine the fork and execlp functions - linux, Assignment What I...

Assignment What I'm covering: General control flow fork() execlp() Parameters Makefiles Additional Questions General Control Flow/fork(

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