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 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.

What are kernels and what do kernels do, What are kernels and what do kerne...

What are kernels and what do kernels do? The kernel is a program that comprises the central core of a computer operating   system. It has entire control over everything that

What is the use of system calls, Q. What is the use of system calls? A...

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

10 marks, Differentiate between sequential access and direct access method?...

Differentiate between sequential access and direct access method?

Explain a computing environment, Q. Polling for an I/O completion is able ...

Q. Polling for an I/O completion is able to waste a large number of CPU cycles if the processor iterates a busy-waiting loop several times before the I/O completes. However if the

Demand paging, Demand paging gives that pages could only be brought into ...

Demand paging gives that pages could only be brought into memory if the running process acts them. This is usually referred to as lazy evaluation as only those pages operated by

What are the issues in designing a network-transparency, Transparency : ...

Transparency : Users must be able to access remote resources as though these resources were local. Transparency should as well promote user mobility. Users must be allowed to lo

Explain the different sections of a process., Explain the different section...

Explain the different sections of a process.     Entry section     Critical section     Exit section     Remainder section Consider a system inclusive of n processe

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