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 kind of operating system is windows xp, Q.  What kind of operating sy...

Q.  What kind of operating system is Windows XP? Describe two of its major features. Answer: A 32 or 64 bit pre-emptive multitasking operating system supporting multiple use

Why high level languages need compiler, Q. Why High level languages need Co...

Q. Why High level languages need Compiler? High level languages - illustrations are COBOL, FORTRAN, PL/I andALGOL - are processed by interpreters andcompilers. A compilers is a

What is logical address space and physical address space, What is logical a...

What is logical address space and physical address space? The set of all logical addresses formed by a program is known as a logical address space; the set of all physical addr

What is critical section?, What is critical section? Every process has ...

What is critical section? Every process has a segment code called the critical section, in which the process may be updating tables, changing variables, writing file and etc. W

What is erd, What is ERD? Entity Relationship Diagram is the graphical ...

What is ERD? Entity Relationship Diagram is the graphical representation of the object relationship pair. It is mostly used in database applications.

What are the three major purposes of an operating system, Q. What are the t...

Q. What are the three major purposes of an operating system? Answer: To offers an environment for a computer user to execute programs on computer hardware in a conveni

Describes responsibilities of the I/O manager, Q. Describes responsibilitie...

Q. Describes responsibilities of the I/O manager? Answer: The I/O manager is responsible for file systems and device drivers and network drivers. The I/O manager keeps follow

Define a daemon process , A daemon is a process that removes itself from t...

A daemon is a process that removes itself from the terminal and disconnected, executes, in the background, waiting for requests and responding to them. It may also be described as

Main advantages of the microkernel approach to system design, What are the ...

What are the main advantages of the microkernel approach to system design? Benefits typically contain the following  (a) Adding a new service does not require modifying the

Communications technique - application interaction protocols, Define the Co...

Define the Communications Techniques - Application interaction protocols    Communications techniques are well defined. They give developer the programmatic mechanism to transf

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