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

Main advantages of the microkernel approach to system design, What are the ...

What are the main advantages of the microkernel approach to system design? Benefits typically contain the following  (a) Adding a new service does not require modifying the

All the explanations of operating system and its types., operating systems ...

operating systems and its types together with its design issues and their examples.

Pages into physical memory, For reading, most operating systems use demand ...

For reading, most operating systems use demand paging. This means that pages are only read from the disk into physical memory when they are needed. In the page table, there is a re

Software Support (Introducing Operating Systems), The questions ask List fo...

The questions ask List four major functions of an OS. My answer: Function 1: Provide a user interface Function 2: Manage files Function 3: Manage hardware Function 4: Manage appli

Define swapping, Define swapping. A process requires being in memory to...

Define swapping. A process requires being in memory to be executed. Though a process can be swapped temporarily out of memory to a backing store and then brought back into memo

Show the multithreading performance, Q. Provide two programming instances i...

Q. Provide two programming instances in which multithreading provides better performance than a single-threaded solution. Answer: (1) A Web server that services every request

Use of c and c++, One reason to learn C and C++ is simply that so much soft...

One reason to learn C and C++ is simply that so much software is written in these languages. A related, butmore fundamental reason, is that C and C++ are relatively low-level, allo

Define seek time and latency time, Define seek time and latency time. T...

Define seek time and latency time. The time taken by the head to move to the appropriate cylinder or track is known as seek time. Once the head is at right track, it must wait

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