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

Define the dossleep(ms) function used in the os/2, Define the DosSleep(ms) ...

Define the DosSleep(ms) Function used in the os/2 DosSleep()  suspends the currently executing  thread for some time interval specified in the  ms parameter. If a value of 0 is

When page fault frequency in an operating system is reduced, When the Page ...

When the Page fault frequency in an operating system is reduced Locality of reference is appropriate to the process

What is symmetric multiprocessing, Symmetric multiprocessing To get ma...

Symmetric multiprocessing To get maximum reliability and efficiency a mode of function called as symmetric multiprocessing is used. In essence, with SMP any program or threads

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

What are the methods for handling deadlocks?, What are the methods for hand...

What are the methods for handling deadlocks ? The technique for handling the deadlocks are: We are able to use protocol to prevent or avoid the deadlock, make sure tha

Demand paging, Demand paging With demand paging, a page is called into...

Demand paging With demand paging, a page is called into memory only when a location on that page is actually indexed during run time. With pre-paging, pages other than the one

Explian integrating a request/response mechanism, Explian Integrating a Req...

Explian Integrating a Request/Response Mechanism Traditional application developers will need to develop a mechanism for communication between requesting (client) and respondin

Explain the novell netware, Explain the Novell NetWare     NetWare does...

Explain the Novell NetWare     NetWare doesn't really have the concept of processes in the architecture, as  the most closely associated element in the NetWare  environment to

Lock revenue variable, Demonstrate that your program (include the program o...

Demonstrate that your program (include the program output as part of the final report) can produce the correct output with the following parameters. For each case comment if the ou

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