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 the facilities of a debug monitor, Facilities of a Debug Monitor ...

Facilities of a Debug Monitor Facilities of a debug monitor are like this: Setting breakpoints in the program Initiating a debug conversation while control reaches

Explain terminal symbols, Explain Terminal Symbols Terminal symbols are...

Explain Terminal Symbols Terminal symbols are literal strings that are forming the input of a formal grammar and cannot be broken down into smaller units with no losing their l

Explain about error detection method, Q. Explain about Error detection meth...

Q. Explain about Error detection method? Error detection: error can occur in CPU, in I/O devices or in memory hardware. Operating system constantly needs to be aware of possi

Ipc, Explain in detail about ipc in linux

Explain in detail about ipc in linux

Explain a method for process migration, Q. Process migration in a heterogen...

Q. Process migration in a heterogeneous network is typically impossible given the differences in architectures and operating systems. Explain a method for process migration across

Paging, Paging full question

Paging full question

Multiprogramming, how response times are reduced by allowing time sharing o...

how response times are reduced by allowing time sharing on top of multiprogramming

Explain file control list and user control list, Q. Researchers have recom...

Q. Researchers have recommended that instead of having an access list associated with each file (specifying which users can access the file and how) we should have a user control

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