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 lead to the concept of paging?, What lead to the concept of paging? ...

What lead to the concept of paging? The main memory is separated into two parts that are one for the resident operating system, and one for the user processes. We may perhaps p

Explain about system software, An operating system act as an intermediary b...

An operating system act as an intermediary between user of a computer and computer hardware. The objective of an operating system is to provide an environment in that a user can ex

Command interpreters, Develop a user mode command interpreter which support...

Develop a user mode command interpreter which support these functions: "list-short" -- just like ls without any options "list-long" -- same as ls -l "change" -- same as cd Your co

What is meant by arm-stickiness, What is meant by arm-stickiness? If on...

What is meant by arm-stickiness? If one or a few processes have a high access rate to data on single track of a storage disk, then they might be monopolizing the device by repe

Explain first fit algorithm, FIRST FIT ALGORITHM Scanning a list along...

FIRST FIT ALGORITHM Scanning a list along with if a free hole is available with necessary space for the process to allocate it allocates the process in that space. The first s

Explain bounded buffer and unbounded buffer, Explain bounded buffer and unb...

Explain bounded buffer and unbounded buffer. Here in a producer-consumer problem the producer process produces information that is consumed by a consumer process. At this time

Linux, how to find ncr value in shell script

how to find ncr value in shell script

What is a resource-allocation graph, What is a resource-allocation graph? ...

What is a resource-allocation graph? Deadlocks can be explained more precisely in terms of a directed graph called a system resource allocation graph. This graph having of a se

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