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 and differentiate programmed and interrupt i/o, Question 1 Explain...

Question 1 Explain the structure of operating system in detail Question 2 Explain the following scheduling algorithm                                     1) First come Firs

How can deadlocks be represented?, How can deadlocks be represented? D...

How can deadlocks be represented? Deadlocks are able to be described in terms of a directed graph called as a system resource-allocation graph. This graph contains of the foll

Explain process state with diagram, Question 1 Explain single Partition Al...

Question 1 Explain single Partition Allocation and Multiple Partition Question 2 What is PCB? What useful information is available in PCB? Question 3 Explain Preemptive and No

Why is rotational latency is not taken in disk scheduling, Why is rotationa...

Why is rotational latency usually not considered in disk scheduling? How would you modify SSTF, SCAN, and C-SCAN to include latency optimization? Most disks do not export their

Explain bounded buffer and unbounded buffer, Explain bounded buffer and unb...

Explain bounded buffer and unbounded buffer. Here in a producer-consumer problem the producer process produces information that is consumed by a consumer process. At this time

Define buffering, Define buffering. A buffer is a memory area that keep...

Define buffering. A buffer is a memory area that keeps data whereas they are transferred among two devices or among a device and an application. Buffering is done for three rea

Explain external fragmentation?, Explain external fragmentation? Extern...

Explain external fragmentation? External fragmentation is the process where the free space and the space still available for use, in a piece of storage become separated into ma

Define system call, Define System Call A system call is a request that ...

Define System Call A system call is a request that is made by any program to the operating system for carrying out tasks - picked from a predefined set - which the said program

Illustrate different ways that threads could be implemented, Q. Multithread...

Q. Multithreading is a commonly utilized programming technique. Illustrate three different ways that threads could be implemented. Describe how these ways compare to the Linux clon

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