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 micro-kernel, Operating Systems 1. Explain Micro-kernel? Specif...

Operating Systems 1. Explain Micro-kernel? Specify the benefits of Micro-kernel? 2. Describe seven state process models used for OS with necessary diagram. Differentiate bet

Paging, ___paging fecthces a page only when needed

___paging fecthces a page only when needed

What is co-operating scheduling?, What is co-operating scheduling? CPU ...

What is co-operating scheduling? CPU scheduling decisions may possibly place under the following four circumstances: 1.      When process switches from the running state to

Scheduler that select process from secondary storage device, A scheduler th...

A scheduler that selects processes from secondary storage device is known as                    Medium term scheduler is a scheduler that selects processes from secondary stor

What is long-term, What is long-term, medium-term, short-term? In a bat...

What is long-term, medium-term, short-term? In a batch system many processes are submitted than are able to be executed immediately. These processes are reel to a mass storage

Explain deadlock, Explain Deadlock Every process in a set of processes ...

Explain Deadlock Every process in a set of processes is waiting for an event which only a process in the set can cause.

System bus and device speeds as the cpu speed increases, Q. Why is it impor...

Q. Why is it important to scale up system bus and device speeds as the CPU speed increases? Answer: Consider a system which carries out 50% I/O and 50% computes. Doubling-up

Dynamic memory management, Usually memory is allocated from a large pool of...

Usually memory is allocated from a large pool of unused memory area called the heap. In C++, dynamic allocation/deallocation must be manually performed using commands like malloc,

Bounded and unbounded buffer, Ask question #Minimum 100 difference between ...

Ask question #Minimum 100 difference between bounded and unbounded buffer words accepted#

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