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

Write a brief note on demand paging, Write a brief note on demand paging. ...

Write a brief note on demand paging. A demand paging is alike to a paging system with swapping. The Processes reside on the secondary memory while we want to implement a proces

Explain fixed partitioning, Explain fixed partitioning. Partitioning ar...

Explain fixed partitioning. Partitioning are the simpler techniques that don't involve virtual memory. Partitioning has been used in numerous variations in operating systems.

Explain process termination - operating system, Process termination A p...

Process termination A process terminates when it finishes implementing its final statement and asks the operating system to delete it by using the exit system call. At that tim

Explain the various methods of file access, Operating Systems 1. Illust...

Operating Systems 1. Illustrate the Microkernel Architecture with suitable diagram. 2. When Deadlock occurs? What are the Necessary Conditions for Deadlock? 3. Describe f

Micro operation, Ask question maxmum words accepted#

Ask question maxmum words accepted#

What is meant by context switch, What is meant by context switch? Switc...

What is meant by context switch? Switching the CPU to another process needs saving the state of the old process and loading the saved state for the latest process. This task is

How file record length should be chosen, How File record length should be c...

How File record length should be chosen File record length should be selected to match the data characteristics

Determine scheduling policy for time-shared operating system, Determine a s...

Determine a scheduling policy that is most suitable for a time-shared operating system   Round-Robin is a scheduling policy that is most suitable for a time-shared operating s

File management, approaches to identify free memory area in a heap

approaches to identify free memory area in a heap

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