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

Explain advantages and inconveniences of ult, ADVANTAGES AND INCONVENIENCES...

ADVANTAGES AND INCONVENIENCES OF ULT Advantages: Thread switching doesn't involve the kernel - no mode switching Scheduling is able to be application specific -

Determine what the expansion of nested macro calls follows, Determine what ...

Determine what the expansion of nested macro calls follows  The expansion of nested macro calls follows the Last in First out (LIFO) rule.

Elimination of common sub expression - code optimizatin, Elimination of com...

Elimination of common sub expression during code optimization An optimizing transformation is a rule for rewriting a section of a program to enhance its execution efficiency wi

What is the purpose of system calls, Q. What is the purpose of system calls...

Q. What is the purpose of system calls? Answer: System calls permit user-level processes to request services of the operating system.

Difference between sam and active directory, Question: (a) Write down ...

Question: (a) Write down short notes on the different versions of Windows server 2003 mentioned below: 1. Windows Server 2003, Web Edition 2. Windows Server 2003, Stand

Exdplain many-to-many model, Many-to-Many Model The many-to-many model-...

Many-to-Many Model The many-to-many model- many user-level threads to many kernel-level threads avoids several of the limitations of the one-to-one model, although extending mu

Allocating new pages, Processes have valid and invalid entries on their pag...

Processes have valid and invalid entries on their page tables. The valid entries all point to some where "real" (e.g. a physical page, or some portion of disk in case of non-reside

What are the different directory structures, What are the different directo...

What are the different directory structures? Explain each type. There are five dissimilar directory structures: 1.      Single level directory 2.      Two level directory

Locks - mutexes, Locks (also known as mutexes, short for mutual exclusion l...

Locks (also known as mutexes, short for mutual exclusion locks) provide mutual exclusion to shared data inside a critical session. They are implemented by means of two atomic routi

Explain the basic method of paging method, Explain the basic method of pagi...

Explain the basic method of paging method. Physical memory is divided into the fixed-sized blocks called frames. Logical memory is as well divided into blocks of the same size

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