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

Describe the possible rmi invocation semantics, Question: (a) Explain t...

Question: (a) Explain the similarities and differences between two different threads running in the same process and two independent processes. When would you want to use two t

Remote it support engineer windows systems administrator, Remote IT Support...

Remote IT Support Engineer Windows Systems Administrator Project Description: Need Windows base IT Support Engineer / Systems Network Administrator - perfectly MCSE qualified

Define input - output operations, Q. Define Input - Output operations? ...

Q. Define Input - Output operations? Serial lines, Disks, tapes and other devices should be communicated with at a very low level. The user require only specify the device and

Differences between foreground and background, Describe the differences bet...

Describe the differences between foreground and background processing. What advantage does background processing provide? 1. Background processes typically run with little or no

What is two-level directory, What is Two-level directory In the two-lev...

What is Two-level directory In the two-level directory structure every user has own user file directory (UFD). When a user jobs begins or a user logs in, the system's master fi

How many disks can be used effectively by one fast wide bus, Q. More than ...

Q. More than one disk drive is able to be attached to a SCSI bus. Especially a fast wide SCSI-II bus can be connected to at most 15 disk drives. Remember that this bus has a bandw

Describe the differences among short-term and medium-term, Describe the dif...

Describe the differences among short-term, medium-term, and long-term scheduling.   Short-term (CPU scheduler)-selects from jobs in memory those jobs that are ready to execu

Define process swapping , Swapping : Whole process is moved from the swap...

Swapping : Whole process is moved from the swap machine to the main memory for execution. Process size must be equal or less than to the used main memory. It is easier to exe

Define the term system software, Question: (a) Define the term system ...

Question: (a) Define the term system software and application software, giving an example for each. (b) Draw a diagram to represent the abstract view of a computer system i

Determine the reasons for poor response time, Determine the reasons for Poo...

Determine the reasons for Poor response time Process busy or High I/O rates or High paging rates

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