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

Is computers protect the operating system, Q. Some untimely computers prot...

Q. Some untimely computers protected the operating system by placing it in a memory partition that couldn't be modified by either the user job or the operating system itself. Expl

Operation management, #question After working for 30 years, Ramjee Somjee D...

#question After working for 30 years, Ramjee Somjee Dutt opted for VRS and started a courier company and did very well in the first four years. He was now looking for expansion of

Explain process scheduling in multiprogramming, Normal 0 false ...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Transferring files from windows to unix, Transferring files from Windows to...

Transferring files from Windows to Unix Be very careful transferring files from Windows to Unix. If you do transfer a file from Windows to Unix open the file, in Unix, using vi

Protection scheme in unix, Q. Consider a system that holds 5000 users. Pre...

Q. Consider a system that holds 5000 users. Presume that you want to allow 4990 of these users to be able to access one file. a. How would you denote this protection scheme in

Semantics for execution of rpcs, Q. Presume that a distributed system is su...

Q. Presume that a distributed system is susceptible to server failure. What mechanisms would be needed to guarantee the exactly once semantics for execution of RPCs? Ans

Bio, how it is work.

how it is work.

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