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 purpose of the checkpoint mechanism, Describe the purpose of t...

Describe the purpose of the checkpoint mechanism. How habitually must checkpoints be performed? Explain how the frequency of checkpoints affects: System performance while no

Show the multithreading performance, Q. Provide two programming instances i...

Q. Provide two programming instances in which multithreading provides better performance than a single-threaded solution. Answer: (1) A Web server that services every request

Multi-level page tables, Multi-level page tables are tree-like structures t...

Multi-level page tables are tree-like structures to hold page tables. As an example, consider a two- level page table, again on a 32-bit architecture with 212 = 4 kbyte pages. Now,

Write xeyes on command line, Ask question #Minimum 100 words accepteWrite a...

Ask question #Minimum 100 words accepteWrite an xeyes command to display a window that is: ? SIZE: ¦ 400 pixels wide ¦ 300 pixels tall ? LOCATION: ¦ 100 pixels from the right edge

Comparing, Compare 2 different operating systems.

Compare 2 different operating systems.

Explain about paging, Explain about paging? Answer: Paging is a memory-...

Explain about paging? Answer: Paging is a memory-management scheme that permits the physical-address space of process to be noncontiguous. Paging avoids the considerable proble

Explain the sleep (ms) function, Explain the Sleep (ms) Function  This ...

Explain the Sleep (ms) Function  This call places the current thread in a suspended state for the number of milliseconds passed as the parameter (ms). After that Windows NT wil

Memory hierarchy, Difference between cache and associate memory

Difference between cache and associate memory

Long term scheduler, Long term scheduler calculates which processes are a...

Long term scheduler calculates which processes are admitted to the machine for processing. It accepts the degree of multiprogramming. Once accepted, a job converts a process.

What is the main advantage of multiprogramming, What is the main advantage ...

What is the main advantage of multiprogramming? Multiprogramming makes efficient use of the CPU by overlapping the demands for the CPU and its I/O devices from various users. I

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