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

Explanation of modern cpu architectures, Your CTO liked your proposal from ...

Your CTO liked your proposal from Unit 2 so much he only trusts you to explain complex concepts to his managers. He now wants you to write him a four page paper explaining the CPU,

Merits of device controller in the kernel, Q. State three merits of placing...

Q. State three merits of placing functionality in a device controller rather than in the kernel and State three disadvantages. Answer: Three advantages: Bugs are less probabl

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

unix script command and echo command, Objectives 1.    Login to UNIX ...

Objectives 1.    Login to UNIX system and logout 2.    Learn features of the vi editor and to use online help (main pages).  Gain experience using them to create a document

Effects of multiprogramming on resource utilization, Effects of multiprogra...

Effects of multiprogramming on resource utilization With the utilize of multiprogramming, batch processing is able to be quite efficient .Just as multiprogramming permits the

Calculate the maximum file size , A UNIX file system has 1-KB blocks and 4-...

A UNIX file system has 1-KB blocks and 4-byte disk addresses. What is the maximum file size if i-nodes contains 10 direct entries, and one single, double, and triple indirect entry

Race condition, list the prevention of mechanism for race condition with op...

list the prevention of mechanism for race condition with operating system

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:

An operating system for a real-time environment, Q. What is the major diffi...

Q. What is the major difficulty that a programmer should overcome in writing an operating system for a real-time environment? Answer: The major difficulty is keeping the oper

What is busy waiting, What is busy waiting? The repeated implementation...

What is busy waiting? The repeated implementation of a loop of code while waiting for an event to happen is known as busy-waiting. The CPU is not engaged in any actual producti

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