If there is one thing which has changed our lives in a big way it is the email facility which has made our lives easier for we can send and receive information in a few seconds. While many have benefited with email facility, one can derive much more benefits with the existing facilities should they follow some discipline.

Users of email have always followed different patterns depending on their personalities.  The perfectionists have always paid importance on grammar, spellings and use of perfect paragraphs much like a letter which used to be typewritten prior to advent of email.  The busy people have always preferred speed over perfection without even being bothered to do a spell check.  There are still a lazy few who have paid importance to beautification by way of fonts and invariably one finds that most of their messages lie in the draft folder than in the sent folder.  While users have chosen different patterns of sending mails there is one thing which many ignore and that is wording of the subject. Subject is one of the most important things and there are some dos and don'ts to be followed and here are some of them:-

1. Never reply to a junk mail especially if you are a relative of the sender:- At workplaces most of us forward junk messages to our colleagues, friends and  relatives.  There are some colleagues who do a simple reply with history on the message saying "good one" or "nice one" which is perfectly acceptable.  Many people especially those who get lot of mails do not bother to open the mail assuming it is a complimentary message saying thanks or a good one.  However the problem is there are people especially relatives who reply on the same message and without changing the subject "how or you" or how are your parents or children or sometimes may be something more important and here lies the problem as many people do not open the mail and I for once had erred because I did not open a mail of my relative assuming it to be a complimentary message.  Through this article I request all not convey hi or a hello through a reply to option on a junk mail because the chances of the mail being opened are rare and it is a perfect invitation for understandings. 

Another problem related to replying on a junk message is that it occupies more space as junk messages usually have huge attachments.  Even if a person opens the mail he would not like to store it because it occupies space.  The person would be overwhelmed by the warmth of the message and the sender but would not be in a position to store the message.  It is therefore suggested that all his or hellos are sent through new memos because those are read and stored as well because it occupies lesser space.

2. Put important details in subject especially in subjects:- If you are sending a mail to a customer asking for a payment against a particular project, please make sure that you enter the payment amount and project name in subject column itself.  On a busy day it becomes easier for the recipient to take action on your mail as he would give preference to a mail on a matter which is known even before opening the mail rather than spend time on others mails where the matter is not known without opening the mail.

3. Change subject wherever required:- You might have received a mail from a customer enquiring about prices with a subject called "Rate Enquiry" and the normal procedure is that you do a reply with history to the mail and quote the prices without changing the subject.  At a later stage when you need the customers address to process the order, you can do a reply with  history on the same mail as usual but by changing the subject to "Address Details Required"  There are many who do not bother to change the subject even though the matter has changed and as a result of that their mails are not read.

4.Ask for return receipts only if required:- At workplaces users have a option of a acknowledgement to their mails i.e. whenever the recipient opens the sent mail the sender gets a automatic acknowledgement from the recipient.  The facility is extremely useful as there are lot of recipients who deny receiving the mail.  However there are also people who mark a return return for every mail including junk mails like jokes.  Imagine a situation a person sends a junk mail to around 50 people and his inbox is flooded with 50 return return receipts.  The 50 return receipts he gets means that his main mails gets hidden in the middle of return receipts and may miss out on reading some important mails.  Apart from the sender has to delete all those return receipts which would mean wasting a few minutes on deletion of those mails.

5. Use reply with history option only if it is mandatory:- There are people who keep on replying with history endlessly even after the subject has changed and as a result of which mailbox becomes full.  The more times you reply on the same message the size of the message becomes bigger and hence difficult to open especially if the connectivity is poor. Please use new memo option if the subject has changed as it helps in opening the mail faster and in storing it among archived mails.

6.Delete all reply with history messages except the last one:- If there are 20 mails with reply with history then retain the last one and delete everything else.  When you get all the information in a single message there is no point in retaining around 20 odd mails which has the same content and one. This also helps in making the search faster if you have thousands of archived mails.

The above mentioned tips if followed could save lot of us time for ourselves and to the recipient of our mails. Always remember one thing it is the subject which counts most in the chances of your mail being read or ignored.

—        Voice chat used to create a voice call interaction. In this process two type of voice transformation as possible

1. with use of vocoder

2. With out use of vocoder

 

—        two types of vocoder used

1. Using first law

2. Using second law

Both of these laws used to convert the analog to digital

 

First law:

• It used to create a small dynamic range. It takes   input data in the size of 13 bit. During the process it converts these 13 bit data into 8 bit data for transfer process.
• In a law it create a small signal distortion

Second law:

 

• It used to create a large dynamic range. It take   input data in the size of 14bit .During the process these 14 bit magnitude by 32 bit for transfer process
• It reduces small signal distortion

 

Many people from us accidentally delete important data and usually ,most of them do not know tow to get it again. Now I tells a free utility that can retrieve your deleted data from hard drive. Name of this utility is "Raid2Raid". It can be downloaded from ' http://raid2raid.com " for free.

This is a powerful utility that not only recovers deleted files , but also reads data from RAID volumes. Hare is four pretty simple steps to recover deleted files from hard disks or USB disks.To recover data from any medium , it needs to be connected and detected by the computer and primer hard drive where the recovered data will be stored should be larger than the capacity of the data to be rescued.

You can also crate an image of the hard drive, particular volume or partition for future analysis. follow these steps to recover your lost data:

• start the utility and double click on any volume or partition from where the data needs to be recovered.
• After few moments a list of files and folder present and deleted on the drive will be displayed. select the ones you need to be recovered
• once the file are selected, right click on any of selected element and click on "recover this file" from context menu
• choose a alternate location for recovered files to be saved and raid2raid start recovering your data

C

History of C

C language was developed in the BELL labs by Dennis Ritchie. The important features of C are drawn from the language called the Basic Combined programming language (BCPL). BCPL is a predecessor to C. the language was developed primarily for developing multi user operating system called UNIX. 80% of the UNIX is developed using c.

 

In 1983, the American national standard institute (ANSI) formed a committee to provide the modern definition of C. This definition was called the “ANSI C”.

 

C is a highly flexible language. It can be used to develop any application ranging from scientific analysis to business data processing. Hence C is called a high level language. C support huge variety of data structures viz. basic data types like integer, floating point (single and double precision), character enumerative, composite data types like structures, unions and pointers.

 

C is also known as middle level language, as C supports lot of low level functions for manipulating memory and CPU registers.

 

This part concerned with the basic elements used to construct simple C statements. These elements include the C character set, identifiers and keywords. These basic elements are combined to form comprehensive program structure.

 

The C character set

C uses upper case letter A-Z, lower case letter a-z, the digits 0-9 and certain special characters as building blocks to form basic program elements. E.g. constants, operators, variables, expressions etc. The special characters are listed below:

+ - * / = % & # ! ? ^ “ ‘ ~ \ | ( ) [ ] { } : ; . , _ (blank space)

C uses certain combination of these characters known as escape sequences or whitespace characters. These special conditions are backspace \b, newline \n, horizontal \t, etc.

Comments

Comments are the text included in a program for explanation purpose. Comments are not executed. They are ignored by compiler. C support two types of comments.

1.Single line comments: single comments starts with // and proceeds up to end of the line.

2. Multiline comments: Any block of text enclosed between /* and */ is taken as comments.

IDENTIFIERS

Identifiers are nothing but names given to various program elements such as variables, constant, functions and arrays. Identifiers are composed of letters both upper and lower case and digits in any order except that the first character should be a letter. Underscore [“_”] is a special character that can be used in an identifier’s name. Underscore is treated as a letter. Thus an identifier can begin with an underscore.

C is a case sensitive. That is ‘max’ and ‘MAX’ is two different identifiers. Keywords cannot be used as identifiers.

 

EXAMPLE

The following are valid identifiers

N             X23         sum_years          _temp

Name    interest_rate     student                                table

The following are not valid identifiers

79:          cannot begin with number

“4^th”:      cannot begins with special characters

System-no:         cannot contain hyphen

Auto:                     it’s a keyword

KEYWORDS

C has a set of reserved words called keywords, which have standard predefined meanings. The usage of keywords solely for their intended purpose. It is illegal to use a keyword as a programmer defined identifier.

The standard keywords are

auto       extern size of   break    float       static     case       for          struct    char       goto       switch   const                     if                typeef  continue              int           union    default long       unsigned             do           register                void       double                return   volatile else        short     while     enum    signed   default

DATA TYPES

Many types of data are supported in C. each of the data types may be represented differently in the computer memories. C supports basic data types and user defined data types. The memory requirement for data types may vary from compiler to compiler.

 

 

Data types	Description	Memory size require
Int	Integer quantity	2 bytes
Char	Single character	1 bytes
Float	Single precision floating point	4 bytes
Double	Double precision floating point	8 bytes

 

The basic data types can be augmented by using data type’s qualifiers viz. short, long, signed and unsigned. For example, an integer can be defined as short int, long int and unsigned int.

A short int require less memory than the ordinary int or it may require the same amount of memory as an ordinary int but it will exceed in ordinary int, in word length.

An unsigned int have the same memory requirement as that of ordinary int. however, in case of ordinary int the left most bit is reserved for the sign. The quantifier unsigned makes the integer to use all the bits to store value, there by altering the range of values that can be stored.

CONSTANT AND LITERALS

An elements whose value is not altered during the execution of the program is called a constant. Even constant have the data types like:

*Integer constant

* Floating point constant

* Character constant

* String constant

* Enumeration constant

Example:

Integer constant-             7              8676       766242  integer constant

Floating point constant-                12.4        -7.154    2E+5

Character constant-        ‘s’           ‘t’            ‘\b’

String constant-                “hello”  “world”                “computer\n”

Unsigned decimal-5000U

Long decimal-    123456789L

Hexadecimal number-   0x62F

Octal number-   0672

Illegal constant:

Illegal character(,)-          10,455

Illegal character(blank space)-    45 656 8

DECLARATIONS

Associating variables or group of variables to a specific type is known as declaration. All variables must be declared before (i.e., in the beginning of the program itself) they are used in the executable statements.

A declaration consists of data types followed by one or more variable names separated by comma and terminated by a semicolon.

Data-types          variable_list;

 

Example:

Int roll_no;

Float average, rating;

Char status;

Short int a,b;

Unsigned int r,s;

Long int r,t;

Double root;

EXPRESSIONS

An expressions may consists of an single entity, such as a constant or a variable name. it may also consist of some combination of such entities interconnected by one or more operators. Most of the expressions in C involves operators.

Expressions can also represent logical condition that is either true or false. C uses 0 to represent false and 1 to represent true. Hence logical expressions are basically numerical expressions.

a+b;       -an arithmetic operation

x=a;       -an assignment expression

c=x+y;   -an arithmetic and assignment operation

c==y;     -condition expression statement checking for equality

i++;        -increment expression sane as i=i+1;

STATEMENT

This is a program construct that carries out some actions. In C, there are three different classes. They are

*Expression statement

*compound statement

*Control statement

Example

1.The following are expression statement

C=7;

C=a+b;

2.compound statement consists of several individual statements enclosed with in a pair of braces{ }.

{

Pi=3.14;

Area=pi*radius*radius;

}

3.control statement

Control statement imolement special program features such as logical test, loops and branches, many control statements are composed of other statements.

While

{

Print(“the value of number=%d”,num);

Num++;

}

SYMBOLIC CONSTANTS

A symbolic constant is the name that substitutes for a sequence of characters. These characters may represent a numeric constant, a string constant or a character constant. Thus symbolic constants enable us to use names in place of numeric constant, a character constant or a string. The processor does the job of substitution. This is known as macro substitution.

Example:

#define MAX 1000

The above segment is a preprocessor directive. Here the name MAX represents the value 1000. The pre processor replaces all the MAX names in the program with the value of 1000.

OPERATORS AND EXPRESSIONS

As we have already seen, C has a rich variety of operators. This huge number of operators fall in to several categories.
Arithmetic operators- There are five arithmetic operators in C.

 

Operator	Purpose
+	Addition
_	Subtraction
*	Multiplication
/	Division
%	Reminder after integer division

 

Division of one integer by another is called integer division. The operation always results in truncated quotients. On the other hand, if division operation is carried with two floating point numbers or with one floating pointing number and one integer, the result will be floating point quotient.

Example:

If X and Y are two variables with values 10 and 3 respectively then,

X+Y=13

X-Y=7

X*Y=30

X/Y=3(INTEGER DIVISION)

X%Y=1

IF X and Y are given values 12.5 and 2.0 respectively then,

X+Y=14.5

X-Y=10.5

X*Y=25.0

X/Y=6.25(FLOATING POINT DIVISION)

NOTE: There is no exponentiation operators in C. however, exponentiation can be carried out by using the library function pow().

Type conversion and casting

When an expression involves operands with different data types, the result is automatically convertedto the data type of the highest precision operands. This is known as implicit type conversion.

 

Example

Suppose that j is an integer whose value is 7 and f is a double precision floating point number whose value is 5.5 and c is a character type variable which represents the characters ‘w’ (ASCII value of w is 119)

J+f=12.5; (double precision)

J+c=126; integer

 

The value expression can be converted to a different data type if desired. This is known as explicit type conversion or casting. The syntax for casting is

(data type) expression;

Example:

Suppose that i=10 and f=3 both integers. Then i/f=3; (integer division)

If

(float) i/f =3.33; (floating point division)

In the example, we have explicitly type converted variable I to floating number.

UNARY OPERATORS

The class of operators that act upon as single operand to produce a result is known as a unary operator. Unary operator usually precede the single operands.

 

Example:

1.The Unary minus(-)

-555           -0x5fff         -0.5

2.The increment (++) and decrement (--) operator

The increment and decrement operators cause their operands to be incremented or decremented by one respectively. There is a difference when these operators are placed before or after their operands.

Example:

Suppose I is an integer whose value is 10 then,

J = ++I;

The value of j is 11. Above expression first increments the value of I and then assigns to j. this is called pre increment operators.

J=i++;

The expression will cause the value of I to be assigned to j first and then incrementation takes place. hence value of j is equal to 10, but value of I is 11. This is called post increment operator. The same rule applies to decrement operator (--) as well.

3. The size of (operand) operator

This operators returns the size of the operands in bytes.

Example

Sizeof(int) =2;

RELATIONAL AND LOGICAL OPERATORS

There are six relation operators in C. they are

Operator	Purpose
<	Less than
>	Greater then
>=	Greater than or equal to
<=	Less than or equal to
==	Equal to
!=	Not equal to

 

These six operators are used to form a logical expression which represents conditions that are either true or false. In C, this is interpreted as zero for false and non-zero for true for true. The non-zero value can be either positive or negative.

 

Example:

Suppose x, y and z are integer variables with values 1, 2 and 3 respectively then

(x

(x+y)>=z              value=non zero

(z!=3)    false      value=zero

(y==2) true         value=non zero

In addition to relational operators, there are two logical operators. They are

Operator	Purpose
&&	AND
||	Or

 

Logical operators act upon operand that is they logical expression. The net effect is to combine the individual logical expression in to more complex condition.

AND operator returns true if either one of the operand is true or both are true. If both operand are false, then the output of OR is also false.

 

Example:

Suppose I is an integer with value 7. F is floating point whose value is 5.5 then,

(I > 6) && (f== 10.0) false

(i==7)|| (f<3.0) true

OPERATOR PRECEDENCE AND ASSOCIATIVITY

Precedence and Associativity control how an expression is evaluated if more than one operator is present in the expression.

Example:

Suppose x=10, y = 5 and’

Z = x + y * 2;

In the above expression, the value of z should be 20. That is y *2 should be evaluated first and then the result should be added with value of x. here we mean to say that * has more precedence that +.

Associativity tells us in what order the expressions are evaluated if more than one some operators with same precedence occur in a statement.

 

Example:

Suppose

Z = x + y -5;

In this expression value of z should be 10. Here + and – have same precedence, but x+y is evaluated first, then 5 is subtracted from the result. That is, the above expression is same as Z = ((x+y)-5). The associativity is known as left to right associativity.

CONDITIONAL OPERATOR

Simple conditional operation can be carried out with conditional operator(?:). The general form of conditional operations is as follow.

(expressions1? expression 2: expression3);

When evaluating a conditional expression , expression1 is evaluated first. If expressional1 is true, then expression2 is evaluated and this becomes the value of conditional expression. However, if expression1 is false, expression3 is evaluated and this becomes the value of conditiona; expression.

 

Example:

Suppose I = 10, then

Z = (i<5) ? 0 : 100;

Here the value of Z should be 100. Since I < 5 is false, the value 100 is assign to Z.

ASSIGNMENT OPERATOR

C has different assignment operators. All of them are used to form assignment expression which assign the value of an expression to an identifier.

The most commonly used assignment operator is “=”, in general form,

Identifier = expression;

 

Example:

A = 10;

Y = m * x + c;

During assignment implicit type conversion may result and this may lead to alteration of data being assigned between different data types.

C contains the following five additional assignment operators: +=, -=, *=, /= and %=.

 

Example:

A = a + b; can be written as

A += b;

This holds good for other operators also.

LIBRARY FUNCTION

Lot of library functions is bundled along with c language. The library function are categorized in to various categories such as standard input and out, mathematical function, string function, type, etc. these library functions are not part of the language though all implementation of the language include them. Anybody who wishes to use these functions should include the appropriate header file where the functions are defined. This inclusion is done by the processor directive.

#include

 

Example:

#include           includes standard input and output

#include          include console input and output

#include          includes string manipulation function.