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

Case studies, Did Abhinav agree to the initial timeline requested by Rebecc...

Did Abhinav agree to the initial timeline requested by Rebecca

Write on short note dma., Write on short note DMA. Direct M emory...

Write on short note DMA. Direct M emory Access (DMA) is a technique for transferring data from  main to a device without passing it through the CPU. Computers that have

Logic gates, Determine the equation for the y and truth table for the circu...

Determine the equation for the y and truth table for the circuits

Explain how protection is provided for the hardware resource, Explain how p...

Explain how protection is provided for the hardware resources by the operating system. Dual mode operation Sharing system resources needs operating system to make sure

Fibonacci sequence, #questionThe Fibonacci sequence is the series of number...

#questionThe Fibonacci sequence is the series of numbers 0,1,1,2,3,5,8,… Formally, it can be expressed as: fib0 = 0 fib1 = 1 fibn = fib n-1 + fib n-2 Write a C program u

How can a user program disturb the normal operation, How can a user program...

How can a user program disturb the normal operation of the system? a) Issuing illegal I/O operation. b) By accessing memory locations within the OS itself. c) Refusing to

What are the benefits of multiprogramming?, What are the benefits of multip...

What are the benefits of multiprogramming? Responsiveness : Multithreading is an interactive application may permit a program to continue running even if part of it is block

What is a message passing system, Question 1 What is a message passing sys...

Question 1 What is a message passing system? Discuss the desirable features of a message passing system Question 2 Discuss the implementation of RPC Mechanism in detail Q

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