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

Virtual addresses, Virtual addresses are made up of two parts: the ?rst par...

Virtual addresses are made up of two parts: the ?rst part is the page number, and the second part is an offset inside that page. Suppose our pages are 4kb (4096 = 212 bytes) long,

Define unix device driver, Define UNIX device driver The UNIX device dr...

Define UNIX device driver The UNIX device driver is structured into two halves called top half and bottom half

What is a pure demand paging, What is a pure demand paging? When starti...

What is a pure demand paging? When starting implementation of a process with no pages in memory, the operating system sets the instruction pointer to the first instruction of t

Explai basic concepts of demand paging, Basic concepts When a process i...

Basic concepts When a process is to be changed in, the pager guesses which pages will be used before the process is changed out again. Instead of swapping in a entire process,

Sector sparing, What is sector sparing is proper definition

What is sector sparing is proper definition

Characteristics of suspend process, Characteristics of suspend process ...

Characteristics of suspend process Suspended process isn't immediately available for execution. The process may or may not be waiting on an event. For preventing t

DOS, Ask question #Minimum 500 words accepted#

Ask question #Minimum 500 words accepted#

Write knowledge base relevant propositional statement, Suppose a logic-base...

Suppose a logic-based agent in the wumpus world has found that locations (1,1) and (2,1) do not contain a stench, but that locations (3,1) and (2,2) do contain a stench. Can the ag

Minor page fault , Minor page fault :I f the page is loaded in memory at t...

Minor page fault :I f the page is loaded in memory at the time the fault is started, but is not checked in the memory management unit as being loaded in memory, then it is named a

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