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

Determine a processing that is not a part of synthesis phase, Determine a p...

Determine a processing that is not a part of Synthesis phase  Perform LC processing is not a part of Synthesis phase

Define the non monolithic coding, Define the Non Monolithic Coding Fir...

Define the Non Monolithic Coding First off, client - server developers must adopt a new programming mindset. Much as with the shift to object - oriented design, developers sho

Semispace, Semispace works by maintaining two disjoint areas from which mem...

Semispace works by maintaining two disjoint areas from which memory can be allocated. These areas are called the from-space and the to-space. At ?rst, the algorithm allocates memor

Define approaches that require knowledge of the system state, Define approa...

Define approaches that require knowledge of the system state?  Answer: Deadlock detection, Deadlock prevention, Deadlock Avoidance.

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

Suggest a scheme for implementing this policy, Q. Consider a calculating e...

Q. Consider a calculating environment where a process is given the privilege of accessing object only n times. Suggest a scheme for implementing this policy. Answer: Add an i

What is time-stamping, time-stamping It is a method proposed by Lampor...

time-stamping It is a method proposed by Lamport, used to sequencing events in a distributed machine without the use of clocks. This process is intended to order events consis

Compute minimum transfer size for acceptable utilization, Q. It is occasio...

Q. It is occasionally said that tape is a sequential-access medium whereas magnetic disk is a random-access medium. In fact the correctness of a storage device for random access d

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