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 a safe state and an unsafe state, What are a safe state and an uns...

What are a safe state and an unsafe state? Answer:  A state is safe if the system can allocate resources to every process in some order and still avoid a deadlock. A system is

Explain a working of file control block, Explain a working of file control ...

Explain a working of file control block A file control block (FCB) has information about the file, containing ownership, permission, and location of the file contents. The log

Pthreads, A thread is defined as an independent stream of instructions that...

A thread is defined as an independent stream of instructions that can be scheduled to run as such by the operating system. Each program contains a number of threads which can be ru

Explain the steps in deadlock recovery, Explain the steps in deadlock recov...

Explain the steps in deadlock recovery. a)      Exterminate off all processes involved - drastic. b)      Exterminate off one at a time till deadlock gone - select a victim.

Mechanism for code and data sharing, Q. Consider a system in which a progr...

Q. Consider a system in which a program is able to be separated into two parts: code and data. The CPU recognizes whether it wants an instruction (instruction fetch) or data (data

Define a layer that is not of an io management module, Define a layer that ...

Define a layer that is not of an IO management module  MCS that is Management Control System is not of an IO management module

Paging, Paging full question

Paging full question

What is critical section?, What is critical section? Every process has ...

What is critical section? Every process has a segment code called the critical section, in which the process may be updating tables, changing variables, writing file and etc. W

Explain indexed allocation, Indexed allocation Indexed allocation bring...

Indexed allocation Indexed allocation bringing all the pointers together into one location: the index block. Every file has its own index block, which is an array of disk-block

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