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

Determine a component of a process precedence sequence, Determine a compone...

Determine a component of a process precedence sequence Process name, Sequence operator ‘;’ and Concurrency operator ‘,’

Windows admin need it, Windows admin need it Project Description: We ...

Windows admin need it Project Description: We want to protect an executable on operating system level , so the process could be visible among all users while the executable r

Estimate the balking rate, People arrive at a barber shop at the rate of on...

People arrive at a barber shop at the rate of one every 4.5 minutes. If the shop is full (it can hold five people altogether), 30% of the potential customers leave and come back i

Principles of informtiona tecnologu, i need to complete project on lan arch...

i need to complete project on lan architceture RAIDs etc

Describe demand-paged environment, Q. Which of the subsequent programming ...

Q. Which of the subsequent programming techniques and structures are good for a demand-paged environment? Which aren't good? Describe your answers. a. Stack b. Hashed symbol

Explain general graph directory, General graph directory The serious pr...

General graph directory The serious problem with using an acyclic-graph structure is ensuring that there are no cycles. When we insert links to an existing tree-structured dire

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

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