fundamentals of computing and c programming - part 1

Presentation By Karthik Srini.

Fundamentals of Computing And C ProgrammingUnit - II - Basics of C Language

Presentation By Karthik Srini.

Basics of C LanguageTokens | Rules | Sample Programs

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TokensTokens are the smallest individual units of a program. Different type of tokens are :

1. Keywords

2. Identifiers

3. Literals (or) Constants

4. Punctuators

5. Operators

Presentation By Karthik Srini.

Keywords

Keywords are the words that convey a special meaning to the language compiler. They are reserved words.

For example,

void , main , int , double , float , for , while , etc…

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Identifiers

Identifiers are the fundamental building blocks of a program and are used in names given to different parts of a program.

For Example,

int number = 10 ; where number is an identifier.

int add ( int a, int b ) where add is an identifier.

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Rules for variable declaration in C• Characters Allowed :

Underscore ( _ )

Capital Letters ( A – Z )

Small Letters ( a – z )

Digits ( 0 – 9 )

• Blanks & Commas are not allowed.

• No Special Symbols other than underscore ( _ ) are allowed.

• First Character should be alphabet or Underscore.

• Variable name Should not be a Reserved Word (or) Keyword

Presentation By Karthik Srini.

Allowed Declarations :

_num=10;

num=10;

num1=10;

num_1=10;

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Declarations that are not allowed Reason

num 1=10; White space between num and 1

23num=10; Declarations can not begin with a number

@num=10; No other special characters except Underscore ( _ ) are allowed

Presentation By Karthik Srini.

LiteralsLiterals are the data items that have fixed data values. They are also known as constants. The types of literals are :

1. Integer Literal

2. Floating Point Literal

3. Character Literal

4. String literal

5. Boolean Literal

6. Null Literal

Presentation By Karthik Srini.

Integer Literal

An integer literal can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal.

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Rules for constructing integer constant

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Floating Point LiteralA floating-point literal has an integer part, a decimal point, a fractional part, and an exponent part. You can represent floating point literals either in decimal form or exponential form.

While representing using decimal form, you must include the decimal point, the exponent, or both and while representing using exponential form, you must include the integer part, the fractional part, or both. The signed exponent is introduced by e or E.

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Few Examples,

3.14159 /* Legal */

314159E-5L /* Legal */

510E /* Illegal: incomplete exponent */

210f /* Illegal: no decimal or exponent */

.e55 /* Illegal: missing integer or fraction */

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Rules for constructing floating point literal

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Illustrative Examples for representation by exponents

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Character Literal

Any character enclosed within single quotes is called a character literal.

For example,

char alphabet = ‘ a ’ ;

char num = ‘ 1 ’ ;

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String Literal

When two or more number of characters are enclosed within double quotes, it is called a string literal.

For example,

char subject = “ Computer Applications ” ;

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Boolean Literal

A boolean literal can take only two values as constant, they are 0 or 1 (i.e.) True or false.

For Example,

boolean flag = 1 ;

boolean is a datatype in Java programming language

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Null Literal

Null literal is normally used to terminate strings.

For example,

‘ \ 0 ’

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Punctuators The different punctuations used in the source code of the program are called Punctuators.

For example,

1. Comma ( , )

2. Semicolon ( ; )

3. Braces - ( ) , { } , [ ] , < >

4. Other Special characters - @ , # , * , & , % , etc…

Presentation By Karthik Srini.

OperatorsOperators are special symbols that perform specific operations on one, two, or three operands, and then return a result. They are classified as :

1. Unary operators - act on only one operand.

2. Binary operators - act on two operands.

3. Ternary operators - act on three operands.

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Unary Operators

Unary operators act only upon one operand.

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Increment : ++x, x++

Decrement : −−x, x−−

Address : &x

Indirection : *x

Positive : +x

Negative : −x

One's complement : ~x

Logical negation : !x

Sizeof : sizeof x, sizeof(type-name)

Cast : (type-name) cast-expression

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Binary Operators

Binary operators are the operators that act upon two operands at the same time.

For example,

Arithmetic operators : + , - , / , %, * , etc…

Logical operators : &&, ! , || , etc…

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Ternary Operator

Ternary operator is that which acts upon three operands, they are also known as conditional operator. ( ? : )

Example,

( num > 10 ) ? max : min ;

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Rules for writing a C Program

•Every C Program Should have exactly one main function•C Program Execution Always Starts from main.•Execution of C Program begins at Opening brace of function and ends at closing brace of the function•Generally all statements in c are written in Lowercase Letters.•Uppercase Letters are used for Symbolic names, output strings and messages•Every C statement must ends with semicolon.

Presentation By Karthik Srini.

Rules for writing a C Program•All variables must be declared with respective data types before using .•C is free form-Language•Comments can be inserted anywhere in C Program , but nested comments are not supported by C .•Braces are Generally Used for the Grouping of statements

Presentation By Karthik Srini.

Sample Program#include<stdio.h> #include<conio.h> void main() { clrscr(); printf(“ Hello world "); getch(); }

Hello World