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 is direct memory access, Direct memory access Many computers avoid...

Direct memory access Many computers avoid burdening the main CPU with programmed I/O by offloading sine if this work to a special-purpose processor known as a direct memory add

Explain the per thread scoping, Explain the Per Thread Scoping Thread-l...

Explain the Per Thread Scoping Thread-level programming introduces new twists for application-level variable scoping. Threads are commonly used in one of two ways. To ex

What is scheduler, What is scheduler? A process migrates among the vari...

What is scheduler? A process migrates among the various scheduling queues throughout its life time. The OS must choose processes from these queues in some fashion. This selecti

How resolution of externally defined symbols is performed, Resolution of ex...

Resolution of externally defined symbols is carried out by    Resolution of externally defined symbols is carried out by Linker

Evolution of operating system, breifly write a note on about evolution of o...

breifly write a note on about evolution of operating system?

File management, five major activities on file management in operating syst...

five major activities on file management in operating system.? Explain it.?

What do you mean by system calls, What do you mean by system calls? Sys...

What do you mean by system calls? System calls give the interface among a process and the operating system. When a system call is implemented, it is treated as by the hardware

What are the typical elements of a process image, What are the typical elem...

What are the typical elements of a process image? User data: Modifiable part of user space. May have program data, user stack area, and programs that might be modified. User

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

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