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 an operating system, What is an operating system? An operating ...

What is an operating system? An operating system is a program that manages the computer hardware. It acts as an intermediate among users of a computer and the computer hardware

Hardware and software requirements for virtual memory?, What are the hardwa...

What are the hardware and software requirements for virtual memory? The hardware required for virtual memory is a secondary memory and page table. The page table should have th

What are the advantages and disadvantages of multithreading, What are the a...

What are the advantages and disadvantages of multithreading?  Advantages : Since by multithreading multiple executions are carried out in the same process environment t

Describe the purpose of the open and close operations, Q. Describe the pur...

Q. Describe the purpose of the open() and close() operations. Answer: The open() operation notifies the system that the named file is about to become active. The c

Explain memory management using bit maps, MEMORY MANAGEMENT USING BIT MAPS ...

MEMORY MANAGEMENT USING BIT MAPS   In this memory is separated into different allocation units each of some particular size(a few bites).consider every space of size 4k. A

Disk scheduling algorithms-first come, FCFS (First Come, First Served) Per...

FCFS (First Come, First Served) Perform operations in order requested No reordering of work queue No starvation every demand is serviced Poor performance

List ways to share directories in operating system, List ways to share file...

List ways to share files among directories in operating systems. a. Copy file from one account into another. b. Link directory entry of "copied" file to directory entry of o

Explain about deadlocks, Q. Explain about Deadlocks? Deadlocks for (...

Q. Explain about Deadlocks? Deadlocks for (int i = 0; i // first find a thread that can finish for (int j = 0; j if (!finish[j]) { boolean temp = true; for

Write note on process, Write note on process, process state? A process ...

Write note on process, process state? A process is in excess of the program code which is sometimes known as text section. It as well includes the current activity as represent

Difference between the vfork() and fork() system call, In the mean while th...

In the mean while the fork() system call the Kernel creates a copy of the parent process's address space and adds it to the child process. But the vfork() system call do no

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