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

Define local procedure call, Q. What kinds of services does the process man...

Q. What kinds of services does the process manager provide? Define local procedure call? Answer: The process manager offers services for creating and deleting and using proce

Sector sparing, What is sector sparing is proper definition

What is sector sparing is proper definition

Server thread, Extend task 1 so that the requests are issued by the clients...

Extend task 1 so that the requests are issued by the clients instead of the server. The server now do not use the "all_requests.dat" file. Instead every client thread reads from

Reference counting, The idea of reference counting is to maintain, for ever...

The idea of reference counting is to maintain, for every object, the total number of references to that object, i.e. the number of "incoming" pointers. Whenever the number of refer

Explain the entry-sequenced file organization, Entry-sequenced file organiz...

Entry-sequenced file organization The records in an entry-sequenced file are store up in the order they are written into the file. New records are for all time appended to

First-in-first-out (fifo), FIFO is named as 'named pipes'. FIFO (first-in-...

FIFO is named as 'named pipes'. FIFO (first-in-first-out) is a special file which is laid to be data transient. Once data is load from named pipe, it cannot be load again. Also, da

Is anti virus a system utility, Problem: a) Explain physically what occ...

Problem: a) Explain physically what occurs when a disk is fragmented. What is the purpose of "defragmenting" a disk? b) What is the idea behind backing up data on a secondar

Linux, what is I/O management Linux

what is I/O management Linux

Define lazy swapper, Define lazy swapper. Rather than swapping the enti...

Define lazy swapper. Rather than swapping the entire process into main memory, a lazy swapper is used. A lazy swapper never swaps a page into memory unless that page will be ne

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