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

Shared stack is used for parameter passing, Q. What protection problems may...

Q. What protection problems may occur if a shared stack is used for parameter passing? Answer: The contents of the stack could be conciliation by other process(es) sharing th

Direct memory access, A-  In a table format, compare between Programmed I/O...

A-  In a table format, compare between Programmed I/O, Interrupt -driven I/O, and Direct Memory Access (DMA) in terms of basic idea, Advantages, disadvantages, and the operating en

Question, A paper mill produces two grades of paper viz., X and Y. Because ...

A paper mill produces two grades of paper viz., X and Y. Because of raw material restrictions, it cannot produce more than 400 tons of grade X paper and 300 tons of grade Y paper i

What is busy waiting?, What is busy waiting? When strict alteration is ...

What is busy waiting? When strict alteration is done there may take place situation like two processes setting their flag as true. Therefore both of the processes have equal pr

Operating systems structures, with the aid of diagrams describe the followi...

with the aid of diagrams describe the following OS structure monolithic,layered and client server.

Illustrate advantages and inconveniences of klt, ADVANTAGES AND INCONVENIEN...

ADVANTAGES AND INCONVENIENCES OF KLT Advantages: the kernel be able to simultaneously schedule many threads of the same process on many processors blocking

Role of discovery and prototype, Discuss the role of discovery and developm...

Discuss the role of discovery and developmental prototypes in defining requirements for this project.Are throwaway prototypes appropriate, or should the project team quickly gather

Explain c-scan , LOOK o Like SCAN except stops moving inwards (or outw...

LOOK o Like SCAN except stops moving inwards (or outwards) when no more requests in that direction exist. C-SCAN (circular scan) o Moves inwards servicing requests u

#title.paging, explain hierarchical,hashed and inverted paging

explain hierarchical,hashed and inverted paging

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