Topics to be coveredIntroduction to CCharacterstics of CCharactersetKeywordsConstantsTypes of constantsSymbolic Constants

Introduction to CC is a general purpose programming language. It was developed at AT & T’s Bell Laboratories of USA IN 1972. It was developed by Dennis Ritchie.

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Characteristics of C1. It is reliable, simple and easy to use.2. There are only 32 Keywords in C.3. It helps to develop structured programs.4. C is highly portable.5. User can add their own functions to the C library.6. C is a format free language.7. It is suitable for Graphics programming.8. Pointer Implementation is available.

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Character SetA character consist of any letter or alphabet, digit or special symbol.Letters Uppercase A-Z

Lowercase a-zDigits All Decimal Digits 0-9Special Symbols + - * / # ? _ < >‘ ; , : “ { } [ ] ( )

White Spaces , Blank Space, Tab

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Keywords Keywords have their predefined meaning. They cannot be redefined by the programmers. They are also known as Reserved Keywords.

There are 32 Keywords in C:Auto Double int structBreak else long switchCase enum register typedefChar extern return unionConst float short unsignedContinue for signed voidDefault goto sizeof volatileDo if static while

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ConstantsConstant that remains unchanged during the execution of the program.

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Constants

Numeric Constants

Character Constatns

Integer Constants

Real Constants

Single Character Constants

String Constants

Types of constantsNumeric Constants

1. Integer Constant: It is a sequence of digits without decimal point.Rules are:1) It must have at least one digit.2) It contains neither a decimal point nor an exponent.3) Commas and blank spaces is not allowed.4) Sign (+ or -) must precede the number.5) Default sign is positive.6) Allowed range is -32768 to 32767

There are three types of integer constants:1) Decimal integers consists of a set of digits 0 to 9.

Examples: 18,-11,+39,0 2) Octal integer constants consists of a set of digits 0 to 7 with a leading

0Examples: 015,0375,0

3) Hexadecimal integer constant consist f a set of digits 0 to 9 or alphabets A(a) to F(f) with a leading 0x or 0X.

Examples: Ox5,ox7d,0x79

2) Real Constants(Floating Point Constants): It is a number that contains either a decimal point or an exponent or both.

Examples: 95.1,B0.012, 2.2e-5,11e+3, 2.3e-3Forms of real constants areA) Fractional form real constants:Rules are:1. A real constant must have atleast one digit.2. It must contain a decimal point.3. Commas and blank spaces is not allowed.4. Sign (+ or -) must precede the number.5. Default sign is positive.6. It could be either positive or negative.

B) Exponential form real constants:Mantissa e exponent

1)The mantissa is either a real number expressed in decimal or an integer.

2) The exponent is always an integer number with an optional plus or minus sign.

3) The mantissa part may have a + or – sign. Default sign is +ve.4) The mantissa part and the exponential part should be separated by a

letter ‘e’.5) Commas and blank spaces is not allowed.6) Allowed range is -3.4e-38 to 3.4e38

Character Constants3) Single Character Constant: A single character constant is a single character enclosed in single quotes. The character may be a letter, number or special character.

Examples: ‘3’,’A’,’c’,”:”

4) String Constants: A string constant is a sequence of characters enclosed in double quotes.

Examples: ‘B.SC.’,’1+3+4’,’V’,”HELLO”

Backslash character constants\n newline character\t tab\’ a single quote\” a double quote

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Symbolic ConstantsFormat for defining for symbolic constants isSyntax:#define symbolicname constantvalueExample: #define pi 3.143

This statement must not end with a semicolon and #define is known as preprocessor.

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