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

Thread pools, Another solution then would be to keep a pool of threads. Whe...

Another solution then would be to keep a pool of threads. Whenever a new task arrives, the system would simply get a thread from pool and set that thread to work on the given task.

Computer number systems, Binary number based systems   Binary is a  ' base...

Binary number based systems   Binary is a  ' base 2' number system, only two numbers exist namely '0' and '1'. Conversion from binary to base 10 is easy if the number column techn

Define the global vs. local variables, Define the Global vs. local variable...

Define the Global vs. local variables It is also important to discuss the scope of resources being granted to the application program.  Variable scoping is defined as the acces

Explain the concept of reentrancy, Concept of Reentrancy   It is a ...

Concept of Reentrancy   It is a useful, memory-saving method for multiprogrammed timesharing machines. A Reentrant method is one in which multiple clients can share a singl

Structures for a file''s data, Q. Likewise some systems support many types ...

Q. Likewise some systems support many types of structures for a file's data while others simply support a stream of bytes. What are the merits in addition to demerits? Answer:

What problems arise if the directory is a general graph, What problems aris...

What problems arise if the directory structure is a general graph? Searching for a particular file may result in searching the similar directory many times. Deletion of the fil

What is segmentation?, SEGMENTATION In a memory management system that ...

SEGMENTATION In a memory management system that is properly a programmer views a program to be collection of program components called as segments . Every segment is a logical

Operating system components, Question 1 Discuss the following with respect ...

Question 1 Discuss the following with respect to Operating Systems: Operating System Components Operating System Services Question 2 Describe the theory behind Pagin

What is an effector process, What is an effector process? The effector ...

What is an effector process? The effector process is a method that verifies itself.The effector process exists in particular criteria.

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