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

Describe the technique of packing, Describe the technique of packing. T...

Describe the technique of packing. The physical record size will not accurately match the length of the desired logical record and the Logical records may even differ in length

Lru implementation details, Now, let us discuss two related algorithms for ...

Now, let us discuss two related algorithms for deciding which pages to evict. The clock algorithm is one of the most popular choices. It works by keeping frames in a circular struc

Request or response interface - interaction using message, Explain the Requ...

Explain the Request or Response interface The Request/Response interface is ideal for a message based client-server interaction. By modeling components to interact via a reque

What do you mean by system calls, What do you mean by system calls? Sys...

What do you mean by system calls? System calls give the interface among a process and the operating system. When a system call is implemented, it is treated as by the hardware

Explain multilevel feedback queue in detail, Explain multilevel feedback qu...

Explain multilevel feedback queue in detail A process can move among the various queues; aging can be executed this way Multilevel-feedback-queue scheduler explained b

Index node (inode), A file system depends on data structures about the file...

A file system depends on data structures about the files, beside the file structure. The former is named metadata-data that defines data. Each file is accumulated with an inode, wh

Exdplain many-to-many model, Many-to-Many Model The many-to-many model-...

Many-to-Many Model The many-to-many model- many user-level threads to many kernel-level threads avoids several of the limitations of the one-to-one model, although extending mu

Explain internal fragmentation, Explain internal fragmentation The Inter...

Explain internal fragmentation The Internal fragmentation signifies to the result of reserving a piece of space without ever intending to use it. This space is wasted that this

For what reason would such a scheme be useful, Q. A Burroughs B7000/B6000 ...

Q. A Burroughs B7000/B6000 MCP file is able to be tagged as sensitive data. When such a file is removed its storage area is overwritten by some random bits. For what reason would

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