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

How does an operating system make multiprogramming possible, How does an op...

How does an operating system make multiprogramming possible by using single processor?

necessary conditions for a deadlock , Q) a. Given that the first three nec...

Q) a. Given that the first three necessary conditions for a deadlock are in place, comment on the feasibility of the following strategy. All processes are given  unique priorities.

Give an overview of windows 2000 file management, Give an overview of WINDO...

Give an overview of WINDOWS 2000 file management. Windows makes use of the NTFS and File Allocation Table file systems. The Older versions of the FAT file system had file name

What is the drawbacks of contiguous allocation of disk space, What are the ...

What are the drawbacks of contiguous allocation of disk space? The disadvantages are a. Suffers from internal fragmentation b. Suffers from external fragmentation c. F

Explain the spawnlp functions used in the netware, Explain the Spawnlp Func...

Explain the Spawnlp Functions Used in the NetWare Spawnlp(flags, execName, arg0,...)  The Spawnlp function is used to load  a NetWare executable file (NLM) specified by exec

What kernel provide for an effective user level thread, 1. What must a kern...

1. What must a kernel provide for an effective user-level thread implementation? 2. With respect to the quantum q in a scheduling algorithm, explain and discuss the impact of th

Important system components, Organizational, Structural, Logical and Execut...

Organizational, Structural, Logical and Execution Relationships Between Important System Components in Linux Kernel Subsystems A. Description of the Project You are require

What is busy waiting, What is busy waiting? The repeated implementation...

What is busy waiting? The repeated implementation of a loop of code while waiting for an event to happen is known as busy-waiting. The CPU is not engaged in any actual producti

Factors involved in choosing the host operating system, 1. How is reliabili...

1. How is reliability enhanced with the microkernel approach to system design?  2. In a virtual machine design where guest operating systems are independent virtual machines sup

Objective, what are the objective of operating system assignment

what are the objective of operating system assignment

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