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 are the major differences between operating systems, Q. What are the m...

Q. What are the major differences between operating systems for mainframe computers and personal computers? Answer: In general operating systems for batch systems have simpler

Deadlocks, At the end of this lecture, and into the next lecture, we will d...

At the end of this lecture, and into the next lecture, we will discuss the last major type of logical error that can occurwhen programming with threads. A deadlock occurswhen two t

Explain wait for graph, Explain Wait for Graph a. Use a resource alloca...

Explain Wait for Graph a. Use a resource allocation graph to derive a wait-for graph.  b. Wait-for graph acquired by making an edge from p 1 to p 2 iff p 1 is waiting for

Computer, what is an operating system?

what is an operating system?

Perl script, Write a Perl script assignGrades.pl to assign letter grades to...

Write a Perl script assignGrades.pl to assign letter grades to the students.

What is mutual exclusion, Question 1 Brief the following distributed compu...

Question 1 Brief the following distributed computing system model Question 2 Explain the components involved in implementation of RPC mechanism Question 3 What is

Deadlock, what are the overall concepts of deadlock

what are the overall concepts of deadlock

How does user specify block to be fetched in direct access, How does user s...

How does user specify block to be fetched in direct access? By specifying the relative block number, relative to first block in file, which is block 0.

How does ntfs handle data structures, Q. How does NTFS handle data structur...

Q. How does NTFS handle data structures? How does NTFS recover from a system crash? What is guaranteed after a recovery takes place? Answer: In NTFS all file-system data stru

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