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

What is meant by the phrase thread-safe, The term thread-safe in computer p...

The term thread-safe in computer programming describes that routine or portion of the program that may be called from multiple programming threads without uncalled for interactions

Operating system strectures, with the aid of diagrams describe the followin...

with the aid of diagrams describe the following os structures monolithic , layered, client server

Explain best fit algorithm, BEST FIT ALGORITHM Here scanning is for th...

BEST FIT ALGORITHM Here scanning is for the finest fit one. Signifies it searches the entire list for the best fit position. For the process therefore in that the process will

What are the different directory structures, What are the different directo...

What are the different directory structures? Explain each type. There are five dissimilar directory structures: 1.      Single level directory 2.      Two level directory

Allocation techniques, Since most of the programs require a lot of memory a...

Since most of the programs require a lot of memory allocation/deallocation, we expect the memory management to be fast, to have low fragmentation, make good use of locality, and be

Explain the novell netware, Explain the Novell NetWare     NetWare does...

Explain the Novell NetWare     NetWare doesn't really have the concept of processes in the architecture, as  the most closely associated element in the NetWare  environment to

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

Nested Macro calls, . Nested Macro calls are expanded using the

. Nested Macro calls are expanded using the

Memory management, 4. Describe priority scheduling algorithm. Consider the ...

4. Describe priority scheduling algorithm. Consider the following set of processes. Show the order in which the algorithm will schedule these processes. Assume preemptive and non-p

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