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

Architects applications by making use of multitasking, Architects Applicati...

Architects Applications by Making Use of Multitasking As the capability of computer hardware keeps increasing, operating systems are presented with overwhelming opportunities.

Define fifo page replacement algorithm, Define FIFO Page Replacement Algori...

Define FIFO Page Replacement Algorithm This policy simply eliminates pages in the order they arrived in the main memory. By using this policy we simply remove a page based upo

Tcp and ip stack, What does the last four digits '0010' of the above dump r...

What does the last four digits '0010' of the above dump represent? What action will the Destination node takes when it receives this packet? The last four digits '0010' denotes

Define secondary memory, Define secondary memory. This memory holds tho...

Define secondary memory. This memory holds those pages that are not there in main memory. The secondary memory is usually a high speed disk. It is called as the swap device, an

Difference between the vfork() and fork() system call, In the mean while th...

In the mean while the fork() system call the Kernel creates a copy of the parent process's address space and adds it to the child process. But the vfork() system call do no

Us constitution, what branch of goverment were the federal courts are?

what branch of goverment were the federal courts are?

Operating system, The term Operating System (OS) is often misused. It is co...

The term Operating System (OS) is often misused. It is common, for example, for people to speak of an OS when they are in fact referring to an OS and to a set of additional applica

Linux kernel components, Example 1.  The diagram illustrating the data stru...

Example 1.  The diagram illustrating the data structures of in-memory VFS objects and on-disk objects and their relationships on slide 24 of the lecture notes OSD.4. This diagram i

Explain file structure, File structure Certain files must conform to a ...

File structure Certain files must conform to a needed structure that is understood by the operating system. The operating system may consist that an executable file has a parti

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