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

Deadlock detection, Deadlocks can be detected while the program is running,...

Deadlocks can be detected while the program is running, by running cycle detection algorithms on the graph that de?nes the current use of resources. De?ne this graph as follows:

What are the functions of virtual file system (vfs), What are the functions...

What are the functions of virtual file system (VFS)? a. It separates file-system-generic operations from their execution defining a clean VFS interface. It permits transparent

Explain swapping technique used in pre-3bsd unix systems?, What are the dis...

What are the disadvantages of swapping technique used in pre-3BSD UNIX systems? If there is excessively much memory contention, processes are swapped out until sufficient

What is linked allocation, What is linked allocation, as detailed in text? ...

What is linked allocation, as detailed in text? Directory has pointers to first and last blocks of file. Every block of file (except last) has pointer to the next block.

Explain message passing system, Message passing system:- The function o...

Message passing system:- The function of message system is to permit processes to communicate with one another without the requirement to resort (option) to shared data. Commun

Write a short note on peer-to-peer computing, Write a short note on peer-to...

Write a short note on peer-to-peer computing. Peer-to-peer (P2P) system model is a kind of distributed OS. In this model, clients and servers aren't distinguished from one anot

Explain peterson''s solution for the critical section problem, Explain the ...

Explain the Peterson's solution for the critical section problem? In Peterson's solution two variables a) flag and b) turn are used as shared variables. If the both shared vari

Merits of device controller in the kernel, Q. State three merits of placing...

Q. State three merits of placing functionality in a device controller rather than in the kernel and State three disadvantages. Answer: Three advantages: Bugs are less probabl

Draw and r chart and an x-bar chart, Thermostats are subjected to rigorous ...

Thermostats are subjected to rigorous testing before they are shipped to air conditioning technicians around the world. Results from the last five samples are shown in the table. 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