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

Explain virtual file systems, Virtual file systems The file-system exec...

Virtual file systems The file-system execution having of three major layers. The first layer is the file-system interface, based on the open, read, write and close calls and fi

Define jobs which are admitted to the system for processing, Define the Job...

Define the Jobs which are admitted to the system for processing is called The Jobs which are admitted to the system for processing is known as long-term scheduling.

What are the objectives for a file management system, What are the objectiv...

What are the objectives for a file management system? To meet the data management wants and requirements of the user, which embrace storage of data and the ability to

Explain about operating system services, Q. Explain about Operating System ...

Q. Explain about Operating System Services? An operating system offers services to programs and to users of those programs. It provided by one environment for execution of

Define semaphore, Define semaphore A semaphore is a protected abstract ...

Define semaphore A semaphore is a protected abstract or variable data type that constitutes the classic method for restricting access to shared resources like shared memory in

Briefly explain process management in windows 2000., Briefly explain proces...

Briefly explain process management in Windows 2000. The Windows 2000 process manager provides for deleting, creating and using threads and processes. It has no knowledge about

What are the issues in designing a network-transparency, Transparency : ...

Transparency : Users must be able to access remote resources as though these resources were local. Transparency should as well promote user mobility. Users must be allowed to lo

Mention some attractive properties of semaphore?, Mention some attractive p...

Mention some attractive properties of semaphore?              The Semaphores aren't provided by hardware. However they have numerous attractive properties: Machine indep

Estimation the number of input - output per second, Q. Remapping of bad bl...

Q. Remapping of bad blocks by sector sparing or else sector slipping could influence performance. Presume that the drive in Subsequent Exercise has a total of 100 bad sectors at r

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