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

Describe the three levels of data abstraction, There are three kinds of D...

There are three kinds of Data Abstraction: Physical level: The minimum level of abstraction defines how data are saved. Logical level: The next bigger level of a

Why is it complicated to protect a system, Q. Why is it complicated to prot...

Q. Why is it complicated to protect a system in which users are allowed to do their own I/O? Answer: In earlier chapters we identified a distinction among kernel and user mod

Operating system, What criteria are important in choosing a file organisati...

What criteria are important in choosing a file organisation?

Virtualization, What factors are involved in choosing the host operating sy...

What factors are involved in choosing the host operating system?

Explain the real time operating system, Explain the Real Time Operating Sys...

Explain the Real Time Operating System A real-time operating system comprises definite, fixed time constraints. Processing should be done in the defined constraints, or the sys

Define secondary memory, Define secondary memory. This memory holds tho...

Define secondary memory. This memory holds those pages that are not there in main memory. The secondary memory is usually a high speed disk. It is called as the swap device, an

Problem of unbalanced loads, Present your own fully documented and tested p...

Present your own fully documented and tested programming example illustrating the problem of unbalanced loads. Describe the use of OpenMP's scheduler as a means of mitigating this

Major advantage of the layered approach to system design, Q. What is the ma...

Q. What is the major advantage of the layered approach to system design? What are the de-merits of using the layered approach? Answer: As in all cases of modular design as well

Memory management, what is hashed page tables & explain of there work & fig...

what is hashed page tables & explain of there work & figure

Starvation, what do you mean by starvation?explain in detail

what do you mean by starvation?explain in detail

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